Assistance apparatus, assistance method, and recording medium

ABSTRACT

An assistance apparatus includes a first wire and a second wire that couple an upper-body belt and a left knee belt to each other on or above a front part and back part of the body of a user, respectively, a third wire and a fourth wire that couple the upper-body belt and a right knee belt to each other on or above the front part and back part of the body of the user, respectively, a motor, a left sensor on the left hand of the user, and a right sensor on the right hand of the user. When a force is applied to the left sensor and no force is applied to the right sensor, the motor makes the tension of the second wire and the third wire greater than the tension of the first wire and the fourth wire. When a force is applied to the right sensor and no force is applied to the left sensor, the motor makes the tension of the first wire and the fourth wire greater than the tension of the second wire and the third wire.

BACKGROUND 1. Technical Field

The present disclosure relates to an assistance apparatus, an assistancemethod, and a recording medium for assisting a wearer in walking.

2. Description of the Related Art

For example, Japanese Unexamined Patent Application Publication No.2009-213538 discloses an assistant outfit for assisting movements ofjoints of a user. The disclosed assistant outfit includes a thigh linkto be attached to a thigh, a thigh restraint band that restrainsmovement of the thigh link, a lower-leg link to be attached to a lowerleg, a lower-leg restraint band that restrains movement of the lower-leglink, and a knee assistant motor that changes the angle between thethigh link and the lower-leg link. Japanese Unexamined PatentApplication Publication (Translation of PCT Application) No. 2016-528940discloses a soft exosuit equipped with an actuator including anoperating member. In the soft exosuit, activation of the actuatorgenerates a moment around a joint of a user wearing the soft exosuit toassist the movement of the user.

SUMMARY

A need exists to provide assistance for movements of a user in differentways in accordance with the state of the user, such as whether the useris carrying an object such as luggage. A specific method for addressingthis issue is not described in Japanese Unexamined Patent ApplicationPublication No. 2009-213538 or Japanese Unexamined Patent ApplicationPublication (Translation of PCT Application) No. 2016-528940.

One non-limiting and exemplary embodiment provides an assistanceapparatus, an assistance method, and a recording medium that provideassistance in accordance with the state of a user.

In one general aspect, the techniques disclosed here feature anassistance apparatus including an upper-body belt to be worn on an upperhalf of a body of a user, a left knee belt to be worn on a left knee ofthe user, a right knee belt to be worn on a right knee of the user, afirst wire that couples the upper-body belt and the left knee belt toeach other on or above a front part of the body of the user, a secondwire that couples the upper-body belt and the left knee belt to eachother on or above a back part of the body of the user, a third wire thatcouples the upper-body belt and the right knee belt to each other on orabove the front part of the body of the user, a fourth wire that couplesthe upper-body belt and the right knee belt to each other on or abovethe back part of the body of the user, at least one motor, a left sensorattachable to a left hand of the user, a right sensor attachable to aright hand of the user, and a control circuit. When the assistanceapparatus assists the user in walking while carrying an object, the atleast one motor generates (i) a tension greater than or equal to a firstthreshold value in the first wire during a first period, the firstperiod being a period of 35% or more and 90% or less of a gait phase ofa left leg of the user, (ii) a tension greater than or equal to thefirst threshold value in the second wire during a second period, thesecond period being a period of 0% or more and 25% or less and 65% ormore and less than 100% of the gait phase of the left leg, (iii) atension greater than or equal to the first threshold value in the thirdwire during a third period, the third period being a period of 35% ormore and 90% or less of a gait phase of a right leg of the user, and(iv) a tension greater than or equal to the first threshold value in thefourth wire during a fourth period, the fourth period being a period of0% or more and 25% or less and 65% or more and less than 100% of thegait phase of the right leg. The control circuit acquires a left sensorvalue from the left sensor and a right sensor value from the rightsensor. The control circuit detects a first condition or a secondcondition, the first condition being a condition in which the leftsensor value is greater than or equal to a second threshold value and inwhich the right sensor value is smaller than the second threshold value,the second condition being a condition in which the right sensor valueis greater than or equal to the second threshold value and in which theleft sensor value is smaller than the second threshold value. When thefirst condition is detected, the at least one motor makes the tension ofthe second wire in the second period and the tension of the third wirein the third period greater than the tension of the first wire in thefirst period and the tension of the fourth wire in the fourth period.When the second condition is detected, the at least one motor makes thetension of the first wire in the first period and the tension of thefourth wire in the fourth period greater than the tension of the secondwire in the second period and the tension of the third wire in the thirdperiod.

It should be noted that general or specific embodiments may beimplemented as a system, an apparatus, a method, an integrated circuit,a computer program, a computer-readable recording medium such as arecording disk, or any selective combination thereof. Thecomputer-readable recording medium includes a non-volatile recordingmedium such as a compact disc-read only memory (CD-ROM).

An assistance apparatus and so on according to aspects of the presentdisclosure can provide assistance in accordance with the state of auser. Additional benefits and advantages of the disclosed embodimentswill become apparent from the specification and drawings. The benefitsand/or advantages may be individually obtained by the variousembodiments and features of the specification and drawings, which neednot all be provided in order to obtain one or more of such benefitsand/or advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a user wearing an assistance apparatusaccording to an embodiment, as viewed from the front;

FIG. 2 is a back view of the user wearing the assistance apparatusillustrated in FIG. 1;

FIG. 3 is a block diagram illustrating a functional configuration of theassistance apparatus according to the embodiment;

FIG. 4 is a diagram schematically illustrating the arrangement ofconstituent elements of the assistance apparatus illustrated in FIG. 1;

FIG. 5 is a diagram illustrating example motions of the right leg of theuser, which are assisted by the assistance apparatus;

FIG. 6A is a diagram illustrating a case where the assistance apparatusaccording to the embodiment assists flexion of the hip joint of the leftleg of the user;

FIG. 6B is a diagram illustrating a case where the assistance apparatusaccording to the embodiment assists flexion of the hip joint of theright leg of the user;

FIG. 7A is a diagram illustrating a case where the assistance apparatusaccording to the embodiment assists extension of the hip joint of theleft leg of the user;

FIG. 7B is a diagram illustrating a case where the assistance apparatusaccording to the embodiment assists extension of the hip joint of theright leg of the user;

FIG. 8 is a diagram illustrating an example of an input section of aninput device included in the assistance apparatus according to theembodiment;

FIG. 9 is a diagram illustrating the arrangement of sensors and so onthat are attached to the body of the user;

FIG. 10A is a diagram illustrating a relationship between contactsensors and the hands of the user;

FIG. 10B is a diagram illustrating an example of a signal of a contactsensor;

FIG. 11 is a diagram illustrating an example of a signal of apressure-sensitive sensor;

FIG. 12 is a diagram illustrating an example of a signal of anacceleration sensor of an inertial measurement unit;

FIG. 13 is a perspective view of a user wearing an assistance apparatusaccording to a modification of the embodiment, as viewed obliquely fromthe front;

FIG. 14 is a front view of the user wearing the assistance apparatusillustrated in FIG. 13;

FIG. 15 is a back view of the user wearing the assistance apparatusillustrated in FIG. 13;

FIG. 16 is a diagram schematically illustrating the arrangement ofconstituent elements of the assistance apparatus illustrated in FIG. 13;

FIG. 17 is a block diagram illustrating a functional configuration ofthe assistance apparatus illustrated in FIG. 13;

FIG. 18 is a diagram illustrating a modification of the arrangement ofwires in the assistance apparatus illustrated in FIG. 13;

FIG. 19 is a diagram illustrating a modification of the arrangement ofwires in the assistance apparatus illustrated in FIG. 13;

FIG. 20 is a diagram illustrating a modification of the arrangement ofwires in the assistance apparatus illustrated in FIG. 13;

FIG. 21 is a diagram illustrating a modification of the arrangement ofwires in the assistance apparatus illustrated in FIG. 13;

FIG. 22A is a diagram illustrating a case where the assistance apparatusaccording to the modification assists flexion of the hip joint of theleft leg of the user;

FIG. 22B is a diagram illustrating a case where the assistance apparatusaccording to the modification assists flexion of the hip joint of theright leg of the user;

FIG. 23A is a diagram illustrating a case where the assistance apparatusaccording to the modification assists extension of the hip joint of theleft leg of the user;

FIG. 23B is a diagram illustrating a case where the assistance apparatusaccording to the modification assists extension of the hip joint of theright leg of the user;

FIG. 24 is a flowchart illustrating an example overall flow of anoperation of the assistance apparatus according to the embodiment forassisting a user;

FIG. 25 is a diagram illustrating an example operation of the assistanceapparatus according to the embodiment for assisting a user in walkingforward while carrying an object;

FIG. 26A is a diagram illustrating an example of how a user carries anobject;

FIG. 26B is a diagram illustrating another example of how a user carriesan object;

FIG. 26C is a diagram illustrating still another example of how a usercarries an object;

FIG. 27 is a diagram illustrating an example operation of the assistanceapparatus according to the embodiment for assisting a user in walkingforward while carrying an object in such a manner that the load appliedto the left hand is larger than the load applied to the right hand;

FIG. 28 is a diagram illustrating another example operation of theassistance apparatus according to the embodiment for assisting a user inwalking forward while carrying an object in such a manner that the loadapplied to the left hand is larger than the load applied to the righthand;

FIG. 29 is a diagram illustrating an example operation of the assistanceapparatus according to the embodiment for assisting a user in walkingforward while carrying an object only in the left hand;

FIG. 30 is a diagram illustrating an example operation of the assistanceapparatus according to the embodiment for assisting a user in walkingforward while carrying an object only in the right hand;

FIG. 31 is a diagram illustrating an example operation of the assistanceapparatus according to the embodiment over a period in which a usercarrying an object only in the left hand stops walking and releases theobject; and

FIG. 32 is a diagram illustrating a modification of the operation of theassistance apparatus according to the embodiment for assisting a user inwalking forward while carrying an object.

DETAILED DESCRIPTION Underlying Knowledge Forming Basis of the PresentDisclosure

The inventors of the present disclosure, or the present inventors, havestudied the techniques described in Japanese Unexamined PatentApplication Publication No. 2009-213538 (hereinafter referred to as“Patent Literature 1”) and Japanese Unexamined Patent ApplicationPublication (Translation of PCT Application) No. 2016-528940(hereinafter referred to as “Patent Literature 2”) mentioned in the“BACKGROUND” section and have examined techniques for supporting, orassisting, a user in walking. The present inventors have focused onchanging states of a user, who is a wearer of an assistance apparatus.For example, it is necessary that an assistance method for a user who iscarrying an object such as luggage be different from an assistancemethod for a user who is carrying no object.

First, the present inventors have examined an assistance apparatus thatassists a user in walking by applying forces generated by motors to theuser through wires. To enable various kinds of assistance on the legs ofa user, the present inventors have developed an assistance apparatusincluding wires, each of which is to be placed so as to extend acrossone of the front of the hip joint of the left leg of the user, the backof the hip joint of the left leg of the user, the front of the hip jointof the right leg of the user, and the back of the hip joint of the rightleg of the user. The present inventors have further developed aconfiguration in which the wires are each coupled to an upper-body beltand a left knee belt or a right knee belt, which are to be attached tothe body of the user, and are accordingly attached to the body of theuser. Thus, the present inventors have devised an assistance apparatushaving a simple configuration.

For example, Patent Literature 1 discloses an assistant outfit includinga rod-shaped thigh link that is attached to a side portion of a thigh,and a rod-shaped lower-leg link that is attached to a side portion of alower leg. The thigh link and the lower-leg link are coupled to a kneeassistant motor. The knee assistant motor is driven to change the angledefined by the thigh link and the lower-leg link, and accordingly theassistant outfit assists flexion and extension of the knee of the user.The thigh link, the lower-leg link, and the knee assistant motor areattached to each of the side portion of the right leg of the user andthe side portion of the left leg of the user, resulting in the assistantoutfit disclosed in Patent Literature 1 having a structure that islarge-scale and complicated for the user. Thus, the assistant outfitplaces a heavy burden on the user.

In Patent Literature 2, tension is applied to connection elements of thesoft exosuit, which is worn on a part of the body of the user from thewaist to a thigh and a lower leg, through a cable placed at the frontpart of the thigh of the user, thereby assisting flexion and extensionof the knee of the user. In the soft exosuit disclosed in PatentLiterature 2, the connection elements and so on, which are attached tothe body of the user, are large-scale and complicated for the user.Thus, the soft exosuit places a heavy burden on the user.

In addition, none of Patent Literatures 1 and 2 discloses the details ofa method for providing assistance in accordance with the state of auser. Accordingly, the present inventors have devised the followingtechnique for providing assistance in accordance with the state of auser by using the assistance apparatus having a simple configurationdescribed above.

An assistance apparatus according to a first aspect of the presentdisclosure includes an upper-body belt to be worn on an upper half of abody of a user, a left knee belt to be worn on a left knee of the user,a right knee belt to be worn on a right knee of the user, a first wirethat couples the upper-body belt and the left knee belt to each other onor above a front part of the body of the user, a second wire thatcouples the upper-body belt and the left knee belt to each other on orabove a back part of the body of the user, a third wire that couples theupper-body belt and the right knee belt to each other on or above thefront part of the body of the user, a fourth wire that couples theupper-body belt and the right knee belt to each other on or above theback part of the body of the user, at least one motor, a left sensorattachable to a left hand of the user, a right sensor attachable to aright hand of the user, and a control circuit. When the assistanceapparatus assists the user in walking while carrying an object, the atleast one motor generates (i) a tension greater than or equal to a firstthreshold value in the first wire during a first period, the firstperiod being a period of 35% or more and 90% or less of a gait phase ofa left leg of the user, (ii) a tension greater than or equal to thefirst threshold value in the second wire during a second period, thesecond period being a period of 0% or more and 25% or less and 65% ormore and less than 100% of the gait phase of the left leg, (iii) atension greater than or equal to the first threshold value in the thirdwire during a third period, the third period being a period of 35% ormore and 90% or less of a gait phase of a right leg of the user, and(iv) a tension greater than or equal to the first threshold value in thefourth wire during a fourth period, the fourth period being a period of0% or more and 25% or less and 65% or more and less than 100% of thegait phase of the right leg. The control circuit acquires a left sensorvalue from the left sensor and a right sensor value from the rightsensor. The control circuit detects a first condition or a secondcondition, the first condition being a condition in which the leftsensor value is greater than or equal to a second threshold value and inwhich the right sensor value is smaller than the second threshold value,the second condition being a condition in which the right sensor valueis greater than or equal to the second threshold value and in which theleft sensor value is smaller than the second threshold value. When thefirst condition is detected, the at least one motor makes the tension ofthe second wire in the second period and the tension of the third wirein the third period greater than the tension of the first wire in thefirst period and the tension of the fourth wire in the fourth period.When the second condition is detected, the at least one motor makes thetension of the first wire in the first period and the tension of thefourth wire in the fourth period greater than the tension of the secondwire in the second period and the tension of the third wire in the thirdperiod.

In the configuration described above, the tension generated in the firstwire can apply an assistance force for flexion to the left leg of theuser, and the tension generated in the third wire can apply anassistance force for flexion to the right leg of the user. The tensiongenerated in the second wire can apply an assistance force for extensionto the left leg of the user, and the tension generated in the fourthwire can apply an assistance force for extension to the right leg of theuser. The assistance apparatus generates a tension greater than or equalto the first threshold value in the first wire during the first periodin the gait phase of the left leg to assist flexion of the left leg, andgenerates a tension greater than or equal to the first threshold valuein the third wire during the third period in the gait phase of the rightleg to assist flexion of the right leg, thereby assisting the user inwalking. Further, the assistance apparatus generates a tension greaterthan or equal to the first threshold value in the second wire during thesecond period in the gait phase of the left leg to assist extension ofthe left leg, and generates a tension greater than or equal to the firstthreshold value in the fourth wire during the fourth period in the gaitphase of the right leg to assist extension of the right leg, therebyassisting the user in walking. The first threshold value may be atension value that allows the user to recognize that the movement of aleg is promoted by a tension generated in a wire, and may be 40 newtons(N), for example.

Further, in the first condition, a force is applied to the left sensor,whereas no force is applied to the right sensor. Thus, it is probablethat the user carries an object only in the left hand and that the loadimposed on the left leg is larger than that on the right leg. In thiscase, the assistance apparatus makes the tensions of the wires differentfrom each other to make the assistance force for extension of the leftleg and the assistance force for flexion of the right leg larger thanthe assistance force for flexion of the left leg and the assistanceforce for extension of the right leg. In the second condition, a forceis applied to the right sensor, whereas no force is applied to the leftsensor. Thus, it is probable that the user carries an object only in theright hand and that the load imposed on the right leg is larger thanthat on the left leg. In this case, the assistance apparatus makes thetensions of the wires different from each other to make the assistanceforce for flexion of the left leg and the assistance force for extensionof the right leg larger than the assistance force for extension of theleft leg and the assistance force for flexion of the right leg. Ineither condition, the assistance force for extension of a leg bearing alarger load is larger than the assistance force for extension of a legbearing a smaller load. The assistance force for extension supports aleg bearing a gravitationally downward load and reduces the burden onthe leg. Accordingly, the assistance apparatus can provide balancedassistance with the burdens on the left and right legs being madeuniform and reduced. In this case, the user can walk by moving the leftand right legs in a well-balanced manner while feeling uniform loadsbeing imposed on the left and right legs. In either condition,furthermore, the assistance force for flexion of a leg bearing a smallerload is larger than the assistance force for flexion of a leg bearing alarger load. Accordingly, the assistance apparatus can assist the userto facilitate walking on a leg bearing a smaller load and can induce theprogress of the user's walking. In addition, the assistance apparatusincreases an assistance force for each of the left and right legs, thusenabling well-balanced assistance for the left and right legs. Thus, theassistance apparatus can provide assistance to the user in accordancewith the state of the user.

An assistance apparatus according to a second aspect of the presentdisclosure includes an upper-body belt to be worn on an upper half of abody of a user, a left knee belt to be worn on a left knee of the user,a right knee belt to be worn on a right knee of the user, a first wirethat couples the upper-body belt and the left knee belt to each other onor above a front part of the body of the user, a second wire thatcouples the upper-body belt and the left knee belt to each other on orabove a back part of the body of the user, a third wire that couples theupper-body belt and the right knee belt to each other on or above thefront part of the body of the user, a fourth wire that couples theupper-body belt and the right knee belt to each other on or above theback part of the body of the user, at least one motor, and a controlcircuit. When the assistance apparatus assists the user in walking whilecarrying an object, the at least one motor generates (i) a tensiongreater than or equal to a first threshold value in the first wireduring a first period, the first period being a period of 35% or moreand 90% or less of a gait phase of a left leg of the user, (ii) atension greater than or equal to the first threshold value in the secondwire during a second period, the second period being a period of 0% ormore and 25% or less and 65% or more and less than 100% of the gaitphase of the left leg, (iii) a tension greater than or equal to thefirst threshold value in the third wire during a third period, the thirdperiod being a period of 35% or more and 90% or less of a gait phase ofa right leg of the user, and (iv) a tension greater than or equal to thefirst threshold value in the fourth wire during a fourth period, thefourth period being a period of 0% or more and 25% or less and 65% ormore and less than 100% of the gait phase of the right leg. The controlcircuit acquires information specifying a hand that carries the object.When the information indicates a left hand of the user, the at least onemotor makes the tension of the second wire in the second period and thetension of the third wire in the third period greater than the tensionof the first wire in the first period and the tension of the fourth wirein the fourth period. When the information indicates a right hand of theuser, the at least one motor makes the tension of the first wire in thefirst period and the tension of the fourth wire in the fourth periodgreater than the tension of the second wire in the second period and thetension of the third wire in the third period.

In the configuration described above, when the left hand is designatedas a hand carrying the object, the assistance apparatus makes thetensions of the wires different from each other to make the assistanceforce for extension of the left leg and the assistance force for flexionof the right leg larger than the assistance force for flexion of theleft leg and the assistance force for extension of the right leg. Whenthe right hand is designated as a hand carrying the object, theassistance apparatus makes the tensions of the wires different from eachother to make the assistance force for flexion of the left leg and theassistance force for extension of the right leg larger than theassistance force for extension of the left leg and the assistance forcefor flexion of the right leg. The load imposed on the leg on the sameside as the hand carrying the object is larger than the load imposed onthe leg on the same side as the hand not carrying the object. In eithercase, the assistance force for extension of a leg bearing a larger loadis larger than the assistance force for extension of a leg bearing asmaller load. Thus, the assistance apparatus can provide balancedassistance with the burdens on the left and right legs being madeuniform and reduced. Furthermore, the assistance force for flexion of aleg bearing a smaller load is larger than the assistance force forflexion of a leg bearing a larger load. Thus, the assistance apparatuscan assist the user to facilitate walking on a leg bearing a smallerload. In addition, the assistance apparatus increases an assistanceforce for each of the left and right legs, thus enabling well-balancedassistance for the left and right legs. Thus, the assistance apparatuscan provide assistance to the user in accordance with the state of theuser.

The assistance apparatus according to the second aspect of the presentdisclosure may further include an interface device. The control circuitmay receive the information via the interface device.

In the configuration described above, in response to receipt of inputfrom a user wearing the assistance apparatus, the assistance apparatuscan determine a hand carrying an object in accordance with thedesignation by the user.

In the assistance apparatuses according to the first and second aspectsof the present disclosure, the left leg may shift from a stance phase toa swing phase during the first period, the left leg may shift from theswing phase to the stance phase during the second period, the right legmay shift from the stance phase to the swing phase during the thirdperiod, and the right leg may shift from the swing phase to the stancephase during the fourth period.

In the configuration described above, the assistance apparatus assistsflexion during the first period in which the left leg shifts from thestance phase to the swing phase, and assists flexion during the thirdperiod in which the right leg shifts from the stance phase to the swingphase. Thus, the assistance apparatus can effectively assist the user inwalking. Further, the assistance apparatus assists extension during thesecond period in which the left leg shifts from the swing phase to thestance phase, and assists extension during the fourth period in whichthe right leg shifts from the swing phase to the stance phase. Thus, theassistance apparatus can effectively assist the user in walking.

In the assistance apparatuses according to the first and second aspectsof the present disclosure, the at least one motor may include a firstmotor, a second motor, a third motor, and a fourth motor. The first wiremay have a first end fixed to the left knee belt, and the first wire mayhave a second end fixed to the first motor. The second wire may have afirst end fixed to the left knee belt, and the second wire may have asecond end fixed to the second motor. The third wire may have a firstend fixed to the right knee belt, and the third wire may have a secondend fixed to the third motor. The fourth wire may have a first end fixedto the right knee belt, and the fourth wire may have a second end fixedto the fourth motor.

In the configuration described above, the assistance apparatus canseparately control the tension of the first wire, the tension of thesecond wire, the tension of the third wire, and the tension of thefourth wire. Thus, the assistance apparatus can provide fine assistance.

The assistance apparatuses according to the first and second aspects ofthe present disclosure may further include a fifth wire that couples theupper-body belt and the left knee belt to each other and that extends onor above the front part of the body of the user in a direction crossinga direction in which the first wire extends, a sixth wire that couplesthe upper-body belt and the left knee belt to each other and thatextends on or above the back part of the body of the user in a directioncrossing a direction in which the second wire extends, a seventh wirethat couples the upper-body belt and the right knee belt to each otherand that extends on or above the front part of the body of the user in adirection crossing a direction in which the third wire extends, and aneighth wire that couples the upper-body belt and the right knee belt toeach other and that extends on or above the back part of the body of theuser in a direction crossing a direction in which the fourth wireextends. When the assistance apparatus assists the user in walking whilecarrying the object, the at least one motor may generate (i) a tensiongreater than or equal to the first threshold value in the first wire andthe fifth wire during the first period, (ii) a tension greater than orequal to the first threshold value in the second wire and the sixth wireduring the second period, (iii) a tension greater than or equal to thefirst threshold value in the third wire and the seventh wire during thethird period, and (iv) a tension greater than or equal to the firstthreshold value in the fourth wire and the eighth wire during the fourthperiod.

In the configuration described above, the tension generated in the firstwire and the tension generated in the fifth wire can apply an assistanceforce for flexion to the left leg of the user. The tension generated inthe second wire and the tension generated in the sixth wire can apply anassistance force for extension to the left leg of the user. The tensiongenerated in the third wire and the tension generated in the seventhwire can apply an assistance force for flexion to the right leg of theuser. The tension generated in the fourth wire and the tension generatedin the eighth wire can apply an assistance force for extension to theright leg of the user. Thus, the assistance apparatus including thefirst to eighth wires can provide assistance similar to that of theassistance apparatus including the first to fourth wires. In addition,the assistance apparatus including the first to eighth wires separatelycontrols the tensions of the first to eighth wires, thereby providingmore types of assistance. For example, the tension generated in thefirst wire and the tension generated in the fifth wire may be the sameor different, and a different type of assistance can be provided in eachcase.

In the assistance apparatuses according to the first and second aspectsof the present disclosure, a time point of 50% of the gait phase of theleft leg may correspond to a time point of 0% of the gait phase of theright leg, and a time point of 50% of the gait phase of the right legmay correspond to a time point of 0% of the gait phase of the left leg.

The assistance apparatuses according to the first and second aspects ofthe present disclosure may further include a memory. The memory maystore a program for controlling the at least one motor. The controlcircuit may control the at least one motor in accordance with theprogram.

The assistance apparatuses according to the first and second aspects ofthe present disclosure may further include a gait sensor that detects agait cycle of the user. The control circuit may calculate the gait phaseof the left leg and the gait phase of the right leg based on a sensorvalue of the gait sensor.

In the configuration described above, the assistance apparatus canassist the user in walking on the basis of a gait phase corresponding toa gait cycle of the user. Thus, the assistance apparatus can provideassistance based on actual user walking.

An assistance method according to the first aspect of the presentdisclosure is an assistance method for assisting a movement of a user byusing wires attached to a body of the user. The assistance methodincludes coupling, using a first wire among the wires, an upper-bodybelt and a left knee belt to each other on or above a front part of thebody of the user, the upper-body belt being a belt to be worn on anupper half of the body of the user, the left knee belt being a belt tobe worn on a left knee of the user; coupling, using a second wire amongthe wires, the upper-body belt and the left knee belt to each other onor above a back part of the body of the user; coupling, using a thirdwire among the wires, the upper-body belt and a right knee belt to eachother on or above the front part of the body of the user, the right kneebelt being a belt to be worn on a right knee of the user; coupling,using a fourth wire among the wires, the upper-body belt and the rightknee belt to each other on or above the back part of the body of theuser; when assisting the user in walking while carrying an object,generating a tension greater than or equal to a first threshold value inthe first wire during a first period, the first period being a period of35% or more and 90% or less of a gait phase of a left leg of the user;generating a tension greater than or equal to the first threshold valuein the second wire during a second period, the second period being aperiod of 0% or more and 25% or less and 65% or more and less than 100%of the gait phase of the left leg; generating a tension greater than orequal to the first threshold value in the third wire during a thirdperiod, the third period being a period of 35% or more and 90% or lessof a gait phase of a right leg of the user; generating a tension greaterthan or equal to the first threshold value in the fourth wire during afourth period, the fourth period being a period of 0% or more and 25% orless and 65% or more and less than 100% of the gait phase of the rightleg; acquiring a left sensor value from a left sensor attached to a lefthand of the user; acquiring a right sensor value from a right sensorattached to a right hand of the user; detecting a first condition or asecond condition, the first condition being a condition in which theleft sensor value is greater than or equal to a second threshold valueand in which the right sensor value is smaller than the second thresholdvalue, the second condition being a condition in which the right sensorvalue is greater than or equal to the second threshold value and inwhich the left sensor value is smaller than the second threshold value;when the first condition is detected, making the tension of the secondwire in the second period and the tension of the third wire in the thirdperiod greater than the tension of the first wire in the first periodand the tension of the fourth wire in the fourth period; and when thesecond condition is detected, making the tension of the first wire inthe first period and the tension of the fourth wire in the fourth periodgreater than the tension of the second wire in the second period and thetension of the third wire in the third period. The tension of the firstwire, the tension of the second wire, the tension of the third wire, andthe tension of the fourth wire are adjusted by a motor that iscontrolled by at least one control circuit. The assistance methodaccording to the first aspect described above can achieve advantagessimilar to those of the assistance apparatus according to the firstaspect of the present disclosure.

An assistance method according to the second aspect of the presentdisclosure is an assistance method for assisting a movement of a user byusing wires attached to a body of the user. The assistance methodincludes coupling, using a first wire among the wires, an upper-bodybelt and a left knee belt to each other on or above a front part of thebody of the user, the upper-body belt being a belt to be worn on anupper half of the body of the user, the left knee belt being a belt tobe worn on a left knee of the user; coupling, using a second wire amongthe wires, the upper-body belt and the left knee belt to each other onor above a back part of the body of the user; coupling, using a thirdwire among the wires, the upper-body belt and a right knee belt to eachother on or above the front part of the body of the user, the right kneebelt being a belt to be worn on a right knee of the user; coupling,using a fourth wire among the wires, the upper-body belt and the rightknee belt to each other on or above the back part of the body of theuser; when assisting the user in walking while carrying an object,generating a tension greater than or equal to a first threshold value inthe first wire during a first period, the first period being a period of35% or more and 90% or less of a gait phase of a left leg of the user;generating a tension greater than or equal to the first threshold valuein the second wire during a second period, the second period being aperiod of 0% or more and 25% or less and 65% or more and less than 100%of the gait phase of the left leg; generating a tension greater than orequal to the first threshold value in the third wire during a thirdperiod, the third period being a period of 35% or more and 90% or lessof a gait phase of a right leg of the user; generating a tension greaterthan or equal to the first threshold value in the fourth wire during afourth period, the fourth period being a period of 0% or more and 25% orless and 65% or more and less than 100% of the gait phase of the rightleg; acquiring information specifying a hand that carries the object;when the information indicates a left hand of the user, making thetension of the second wire in the second period and the tension of thethird wire in the third period greater than the tension of the firstwire in the first period and the tension of the fourth wire in thefourth period; and when the information indicates a right hand of theuser, making the tension of the first wire in the first period and thetension of the fourth wire in the fourth period greater than the tensionof the second wire in the second period and the tension of the thirdwire in the third period. The tension of the first wire, the tension ofthe second wire, the tension of the third wire, and the tension of thefourth wire are adjusted by a motor that is controlled by at least onecontrol circuit. The assistance method according to the second aspectdescribed above can achieve advantages similar to those of theassistance apparatus according to the second aspect of the presentdisclosure.

The assistance method according to the second aspect of the presentdisclosure may further include acquiring the information via aninterface device.

In the assistance methods according to the first and second aspects ofthe present disclosure, the left leg may shift from a stance phase to aswing phase during the first period, the left leg may shift from theswing phase to the stance phase during the second period, the right legmay shift from the stance phase to the swing phase during the thirdperiod, and the right leg may shift from the swing phase to the stancephase during the fourth period.

In the assistance methods according to the first and second aspects ofthe present disclosure, a first end of the first wire may be fixed tothe left knee belt, and a second end of the first wire may be fixed to afirst motor among the at least one motor. A first end of the second wiremay be fixed to the left knee belt, and a second end of the second wiremay be fixed to a second motor among the at least one motor. A first endof the third wire may be fixed to the right knee belt, and a second endof the third wire may be fixed to a third motor among the at least onemotor. A first end of the fourth wire may be fixed to the right kneebelt, and a second end of the fourth wire may be fixed to a fourth motoramong the at least one motor.

The assistance methods according to the first and second aspects of thepresent disclosure may further include coupling, using a fifth wireamong the wires, the upper-body belt and the left knee belt to eachother, the fifth wire extending on or above the front part of the bodyof the user in a direction crossing a direction in which the first wireextends; coupling, using a sixth wire among the wires, the upper-bodybelt and the left knee belt to each other, the sixth wire extending onor above the back part of the body of the user in a direction crossing adirection in which the second wire extends; coupling, using a seventhwire among the wires, the upper-body belt and the right knee belt toeach other, the seventh wire extending on or above the front part of thebody of the user in a direction crossing a direction in which the thirdwire extends; coupling, using an eighth wire among the wires, theupper-body belt and the right knee belt to each other, the eighth wireextending on or above the back part of the body of the user in adirection crossing a direction in which the fourth wire extends; whenassisting the user in walking while carrying the object, generating atension greater than or equal to the first threshold value in the firstwire and the fifth wire during the first period; generating a tensiongreater than or equal to the first threshold value in the second wireand the sixth wire during the second period; generating a tensiongreater than or equal to the first threshold value in the third wire andthe seventh wire during the third period; and generating a tensiongreater than or equal to the first threshold value in the fourth wireand the eighth wire during the fourth period.

In the assistance methods according to the first and second aspects ofthe present disclosure, a time point of 50% of the gait phase of theleft leg may correspond to a time point of 0% of the gait phase of theright leg, and a time point of 50% of the gait phase of the right legmay correspond to a time point of 0% of the gait phase of the left leg.

The assistance methods according to the first and second aspects of thepresent disclosure may further include acquiring a sensor value of agait sensor that detects a gait cycle of the user; and calculating thegait phase of the left leg and the gait phase of the right leg based onthe sensor value.

A recording medium according to the first aspect of the presentdisclosure is a recording medium storing a control program for causing adevice including a processor to execute a process. The recording mediumis a non-volatile, computer-readable medium. A first wire couples anupper-body belt and a left knee belt to each other on or above a frontpart of a body of a user, the upper-body belt being a belt to be worn onan upper half of the body of the user, the left knee belt being a beltto be worn on a left knee of the user. A second wire couples theupper-body belt and the left knee belt to each other on or above a backpart of the body of the user. A third wire couples the upper-body beltand a right knee belt to each other on or above the front part of thebody of the user, the right knee belt being a belt to be worn on a rightknee of the user. A fourth wire couples the upper-body belt and theright knee belt to each other on or above the back part of the body ofthe user. The process includes, when assisting the user in walking whilecarrying an object, causing at least one motor to generate a tensiongreater than or equal to a first threshold value in the first wireduring a first period, the first period being a period of 35% or moreand 90% or less of a gait phase of a left leg of the user; causing theat least one motor to generate a tension greater than or equal to thefirst threshold value in the second wire during a second period, thesecond period being a period of 0% or more and 25% or less and 65% ormore and less than 100% of the gait phase of the left leg; causing theat least one motor to generate a tension greater than or equal to thefirst threshold value in the third wire during a third period, the thirdperiod being a period of 35% or more and 90% or less of a gait phase ofa right leg of the user; causing the at least one motor to generate atension greater than or equal to the first threshold value in the fourthwire during a fourth period, the fourth period being a period of 0% ormore and 25% or less and 65% or more and less than 100% of the gaitphase of the right leg; acquiring a left sensor value from a left sensorattached to a left hand of the user; acquiring a right sensor value froma right sensor attached to a right hand of the user; detecting a firstcondition or a second condition, the first condition being a conditionin which the left sensor value is greater than or equal to a secondthreshold value and in which the right sensor value is smaller than thesecond threshold value, the second condition being a condition in whichthe right sensor value is greater than or equal to the second thresholdvalue and in which the left sensor value is smaller than the secondthreshold value; when the first condition is detected, making thetension of the second wire in the second period and the tension of thethird wire in the third period greater than the tension of the firstwire in the first period and the tension of the fourth wire in thefourth period; and when the second condition is detected, making thetension of the first wire in the first period and the tension of thefourth wire in the fourth period greater than the tension of the secondwire in the second period and the tension of the third wire in the thirdperiod. The recording medium according to the first aspect describedabove can achieve advantages similar to those of the assistanceapparatus according to the first aspect of the present disclosure.

A recording medium according to the second aspect of the presentdisclosure is a recording medium storing a control program for causing adevice including a processor to execute a process. The recording mediumis a non-volatile, computer-readable medium. A first wire couples anupper-body belt and a left knee belt to each other on or above a frontpart of a body of a user, the upper-body belt being a belt to be worn onan upper half of the body of the user, the left knee belt being a beltto be worn on a left knee of the user. A second wire couples theupper-body belt and the left knee belt to each other on or above a backpart of the body of the user. A third wire couples the upper-body beltand a right knee belt to each other on or above the front part of thebody of the user, the right knee belt being a belt to be worn on a rightknee of the user. A fourth wire couples the upper-body belt and theright knee belt to each other on or above the back part of the body ofthe user. The process includes, when assisting the user in walking whilecarrying an object, causing at least one motor to generate a tensiongreater than or equal to a first threshold value in the first wireduring a first period, the first period being a period of 35% or moreand 90% or less of a gait phase of a left leg of the user; causing theat least one motor to generate a tension greater than or equal to thefirst threshold value in the second wire during a second period, thesecond period being a period of 0% or more and 25% or less and 65% ormore and less than 100% of the gait phase of the left leg; causing theat least one motor to generate a tension greater than or equal to thefirst threshold value in the third wire during a third period, the thirdperiod being a period of 35% or more and 90% or less of a gait phase ofa right leg of the user; causing the at least one motor to generate atension greater than or equal to the first threshold value in the fourthwire during a fourth period, the fourth period being a period of 0% ormore and 25% or less and 65% or more and less than 100% of the gaitphase of the right leg; acquiring information specifying a hand thatcarries the object; when the information indicates a left hand of theuser, making the tension of the second wire in the second period and thetension of the third wire in the third period greater than the tensionof the first wire in the first period and the tension of the fourth wirein the fourth period; and when the information indicates a right hand ofthe user, making the tension of the first wire in the first period andthe tension of the fourth wire in the fourth period greater than thetension of the second wire in the second period and the tension of thethird wire in the third period. The recording medium according to thesecond aspect described above can achieve advantages similar to those ofthe assistance apparatus according to the second aspect of the presentdisclosure.

It should be noted that the general or specific aspects described abovemay be implemented as a system, an apparatus, a method, an integratedcircuit, a computer program, or a computer-readable recording mediumsuch as a recording disc, or any selective combination thereof. Examplesof the computer-readable recording medium include a non-volatilerecording medium such as a CD-ROM.

Embodiment

The following specifically describes an assistance apparatus and so onaccording to an embodiment of the present disclosure with reference tothe drawings. The following embodiment describes general or specificexamples. Numerical values, shapes, constituent elements, arrangementpositions and connection forms of the constituent elements, steps, theorder of the steps, and so on in the following embodiment are merelyexamples and are not intended to limit the present disclosure. Theconstituent elements mentioned in the following embodiment are describedas optional constituent elements unless they are specified inindependent claims that define the present disclosure in its broadestconcept. The following description of the embodiment may includeexpressions with the term “approximately”, such as approximatelyparallel or approximately perpendicular. For example, the expression“approximately parallel” is used to mean not only the state of beingexactly parallel but also the state of being substantially parallel,that is, the state of being parallel with an error of several percent,for example. This also applies to other expressions with“approximately”. In addition, the drawings are illustrative and are notto scale. In the drawings, substantially the same constituent elementsare given the same numerals and will not be repeatedly described or willbe described in brief.

In this embodiment, an assistance apparatus 100 will be described as anassistance apparatus that assists a user wearing the assistanceapparatus 100 in walking. Specifically, the assistance apparatus 100according to the embodiment will be described as an assistance apparatusthat actively supports flexion and extension of the hip joints of theuser to allow the user to walk. In this embodiment, the term “activelysupporting” may refer not only to supporting flexion and extensionforces, which are required for the hip joints, during flexion andextension of the hip joints of the user to walk in the direction oftravel but also to applying a force for causing flexion and extension ofthe hip joints and to physically controlling the amount of flexion andextension of the hip joints to the desired amount of flexion andextension, that is, physically controlling movements of the hip jointsof the user. As used herein, the term “assisting the user” by theassistance apparatus 100 is used to include both actively supporting themovement of the user and supporting the movement of the user in anauxiliary manner.

1. Configuration of Assistance Apparatus according to Embodiment

The assistance apparatus 100 according to the embodiment will bedescribed with reference to FIG. 1 to FIG. 3. FIG. 1 is a front view ofa user 1 wearing the assistance apparatus 100 according to theembodiment, as viewed from the front. FIG. 2 is a back view of the user1 wearing the assistance apparatus 100 illustrated in FIG. 1. FIG. 3 isa block diagram illustrating a functional configuration of theassistance apparatus 100 according to the embodiment.

As illustrated in FIG. 1 to FIG. 3, the assistance apparatus 100includes an upper-body belt 111, a left knee belt 112 a, a right kneebelt 112 b, and wires 110. The assistance apparatus 100 further includesmotors 114, force sensors 115, and a control unit 120 that controls theoperation of the motors 114. The assistance apparatus 100 may include apower supply 130 for supplying electric power to the motors 114 and soon. The power supply 130 may be, for example, a primary battery, asecondary battery, or the like.

The wires 110 include wires 110 a 1 to 110 a 4. Each of the wires 110 iscoupled to the upper-body belt 111 and the left knee belt 112 a orcoupled to the upper-body belt 111 and the right knee belt 112 b.

The motors 114 include motors 114 a 1 to 114 a 4. The wire 110 a 1 iscoupled to the motor 114 a 1. The wire 110 a 2 is coupled to the motor114 a 2. The wire 110 a 3 is coupled to the motor 114 a3. The wire 110 a4 is coupled to the motor 114 a 4.

The force sensors 115 include force sensors 115 a 1 to 115 a 4. Theforce sensor 115 a 1 is disposed on the wire 110 a 1. The force sensor115 a 2 is disposed on the wire 110 a 2. The force sensor 115 a 3 isdisposed on the wire 110 a 3. The force sensor 115 a 4 is disposed onthe wire 110 a 4.

The upper-body belt 111 is worn on the upper half of the body of theuser 1. The upper-body belt 111 has a band shape, for example. Theupper-body belt 111 includes, near an end portion thereof, a fixingmember. Examples of the fixing member include a hook-and-loop fastenersuch as a Velcro (registered trademark) tape, a fastener such as a hookor a buckle, and a tape. For example, the upper-body belt 111 is wrappedaround the waist of the user 1 and is kept wrapped around the waist ofthe user 1 by using the fixing member. Thus, the upper-body belt 111 isworn on the waist of the user 1. The fixing position of the fixingmember is adjusted to change the inner diameter of the wrappedupper-body belt 111. Since the length of the upper-body belt 111 can beadjusted, various users 1 with different waist circumferences can wearthe upper-body belt 111. The upper-body belt 111 is made of anon-extensible material, for example. Thus, the upper-body belt 111 isless deformable when pulled by the wires 110. The term “upper half ofthe body”, as used herein, is used to include a portion of the body ofthe user from the shoulder to the waist. The upper-body belt 111illustrated in FIG. 1 and FIG. 2 has a configuration of a waist belt tobe worn on the waist of the user 1. The upper-body belt 111 may be wornon, for example, the waist of the user 1 and/or the shoulder of the user1 and/or the chest of the user 1.

The upper-body belt 111 may have a tubular shape. In this case, thetubular-shaped upper-body belt 111 may have a larger circumference thanthe waist circumference of the user 1. The upper-body belt 111 has anadjustment mechanism for adjusting the length of the upper-body belt 111so that the upper-body belt 111 fits the waist of the user 1. Theadjustment mechanism is, for example, a hook-and-loop fastener and maybe configured such that a portion of the hook-and-loop fastener having ahook surface is located on an outer periphery of the tubular shape insuch a manner as to branch from the outer periphery and a loop surfaceof the hook-and-loop fastener is located on an outer peripheral surfaceof the tubular shape. That is, the upper-body belt 111 folds back at theportion of the hook-and-loop fastener, and the inner diameter of thetube formed by the upper-body belt 111 changes in accordance with theamount of fold-back.

The left knee belt 112 a is worn on the left leg of the user 1 in thevicinity of the left knee, and the right knee belt 112 b is worn on theright leg of the user 1 in the vicinity of the right knee. The left kneebelt 112 a may be worn on any portion of the left leg in a regionextending from below the knee to the thigh. The right knee belt 112 bmay be worn on any portion of the right leg in a region extending frombelow the knee to the thigh. That is, the term “knee”, as used herein,may be used to include a region extending from below the knee to thethigh.

Each of the knee belts 112 a and 112 b has a band shape, for example,and includes, near an end portion thereof, a fixing member. The kneebelts 112 a and 112 b are the knee left belt 112 a and the right kneebelt 112 b. Examples of the fixing member include a hook-and-loopfastener such as a Velcro (registered trademark) tape, a fastener suchas a hook or a buckle, and a tape. Each of the knee belts 112 a and 112b is worn on a corresponding one of the thighs of the user 1 or above acorresponding one of the knees of the user 1. For example, each of theknee belts 112 a and 112 b is wrapped around the corresponding one ofthe thighs or the like of the user 1 and is kept wrapped around thecorresponding one of the thighs or the like of the user 1 by using thefixing member. Thus, the knee belts 112 a and 112 b are worn on thethighs or the like of the user 1. The fixing positions of the fixingmembers are adjusted to change the respective inner diameters of thewrapped knee belts 112 a and 112 b. Since the lengths of the knee belts112 a and 112 b can be adjusted, various users 1 having different legcircumferences can wear the knee belts 112 a and 112 b. The knee belts112 a and 112 b may not necessarily be worn over the knee joints. Thehuman thigh has a feature in that the diameter of the thigh becomeslarger gradually from the knee toward the hip. Thus, the knee belts 112a and 112 b, which are worn on the thighs, namely, above the knees, slipjust a little even under tensile forces of the wires 110 when the kneebelts 112 a and 112 b are tightly fastened. In addition, the knee belts112 a and 112 b are made of a non-extensible material, for example.Thus, the knee belts 112 a and 112 b are less deformable when pulled bythe wires 110.

Each of the knee belts 112 a and 112 b may have a tubular shape. In thiscase, the tubular-shaped knee belts 112 a and 112 b may have largercircumferences than the thighs of the user 1. The knee belts 112 a and112 b have each an adjustment mechanism for adjusting the length of thecorresponding one of the knee belts 112 a and 112 b so that the kneebelts 112 a and 112 b fit the thighs or the like of the user 1. Each ofthe adjustment mechanisms is, for example, a hook-and-loop fastener andmay be configured such that a portion of the hook-and-loop fastenerhaving a hook surface is located on an outer periphery of the tubularshape in such a manner as to branch from the outer periphery and a loopsurface of the hook-and-loop fastener is located on an outer peripheralsurface of the tubular shape. That is, the knee belts 112 a and 112 beach fold back at the portion of the hook-and-loop fastener, and theinner diameter of the tube formed by each of the knee belts 112 a and112 b changes in accordance with the amount of fold-back.

The motors 114 are arranged on the upper-body belt 111 in a fixedmanner. In this embodiment, the motors 114 include four motors 114 a 1to 114 a 4. For example, the motors 114 a 1 to 114 a 4 may beaccommodated in hollow containers 111 a 1 to 111 a 4 included in theupper-body belt 111, respectively. The containers 111 a 1 to 111 a 4 maybe integrated with the upper-body belt 111 or may be removably attachedto the upper-body belt 111. The containers 111 a 1 to 111 a 4 may bedisposed in the manner illustrated in FIG. 1 and FIG. 2. In the exampleillustrated in FIG. 1 and FIG. 2, the containers 111 a 1, 111 a 2, 111 a3, and 111 a 4 are located on the left side of the front part, the leftside of the back part, the right side of the front part, and the rightside of the back part of the body of the user 1, respectively. Themotors 114 a 1, 114 a 2, 114 a 3, and 114 a 4 are accommodated in thecontainers 111 a1, 111 a 2, 111 a 3, and 111 a 4, respectively. Themotor 114 a 1 changes the length of the wire 110 a 1 between theupper-body belt 111 and the left knee belt 112 a to adjust the tensionof the wire 110 a 1. The motor 114 a 2 changes the length of the wire110 a 2 between the upper-body belt 111 and the left knee belt 112 a toadjust the tension of the wire 110 a 2. The motor 114 a 3 changes thelength of the wire 110 a 3 between the upper-body belt 111 and the rightknee belt 112 b to adjust the tension of the wire 110 a 3. The motor 114a 4 changes the length of the wire 110 a 4 between the upper-body belt111 and the right knee belt 112 b to adjust the tension of the wire 110a 4.

In this embodiment, each of the motors 114 a 1 to 114 a 4 includes apulley, a drive shaft for rotating the pulley, and an electric motor fordriving the drive shaft to rotate. The pulley of each of the motors 114a 1 to 114 a 4 has a corresponding wire among the wires 110 a 1 to 110 a4 wound therearound. The motors 114 a 1 to 114 a 4 and the wires 110 a 1to 110 a 4 have a one-to-one correspondence. The respective pulleys,drive shafts, and electric motors of the motors 114 a 1 to 114 a 4 areaccommodated in the containers 111 a 1 to 111 a 4, respectively. Each ofthe motors 114 a 1 to 114 a 4 may include an electric motor, but mayinclude no pulley or drive shaft. Alternatively, the upper-body belt 111may include pulleys and drive shafts, each pulley and drive shaft beingassociated with one of the motors 114 a 1 to 114 a 4. In this case, arotating shaft of the electric motor is coupled to the drive shaft forthe pulley in such a manner that a rotational driving force can betransmitted to the drive shaft. Instead of the motors 114 a 1 to 114 a4, for example, a device capable of adjusting the lengths of the wires110 a 1 and 110 a 2 between the upper-body belt 111 and the left kneebelts 112 a and the lengths of the wires 110 a 3 and 110 a 4 between theupper-body belt 111 and the right knee belt 112 b, such as a linearactuator or a pneumatic or hydraulic piston, may be used. In theassistance apparatus 100 having the configuration described above, thewound portions of the wires 110 a 1 to 110 a 4 and the motors 114 a 1 to114 a 4 are located on the upper-body belt 111, and the wires 110 a 1 to110 a 4 and the knee belts 112 a and 112 b are located below theupper-body belt 111. Accordingly, the assistance apparatus 100 achievesa simple and compact configuration.

In this embodiment, the wires 110 include four wires 110 a 1 to 110 a 4.The motor 114 a 1 is coupled to the wire 110 a 1, the motor 114 a 2 iscoupled to the wire 110 a 2, the motor 114 a 3 is coupled to the wire110 a 3, and the motor 114 a 4 is coupled to the wire 110 a 4 so as toindividually adjust the lengths of the wires 110 a 1 to 110 a 4.

Each of the wires 110 a 1 and 110 a 2 has one end fixed to the left kneebelt 112 a. The wire 110 a 1 has another end coupled to the motor 114 a1, and the wire 110 a 2 has another end coupled to the motor 114 a 2.That is, the other end of the wire 110 a 1 and the other end of the wire110 a 2 are fixed. The wire 110 a 1 couples the left knee belt 112 a andthe motor 114 a 1 to each other, and the wire 110 a 2 couples the leftknee belt 112 a and the motor 114 a 2 to each other.

Each of the wires 110 a 3 and 110 a 4 has one end fixed to the rightknee belt 112 b. The wire 110 a 3 has another end coupled to the motor114 a 3, and the wire 110 a 4 has another end coupled to the motor 114 a4. That is, the other end of the wire 110 a 3 and the other end of thewire 110 a 4 are fixed. The wire 110 a 3 couples the right knee belt 112b and the motor 114 a 3 to each other, and the wire 110 a 4 couples theright knee belt 112 b and the motor 114 a 4 to each other.

In this embodiment, each of the motors 114 a 1 to 114 a 4 rotates thepulley in the forward or reverse direction to wind or unwind thecorresponding wire among the wires 110 a 1 to the 110 a 4 around thepulley. The wires 110 a 1 to 110 a 4 described above are fixed to thewaist of the user 1 by the upper-body belt 111 and are fixed to the leftand right thighs or the like of the user 1 by the knee belts 112 a and112 b.

As described above, each of the wires 110 a 1 to 110 a 4 couples theupper-body belt 111 to the left knee belt 112 a or the right knee belt112 b. The wires 110 a 1 to 110 a 4 may be coupled to the upper-bodybelt 111 directly or indirectly. Each of the wires 110 a 1 to 110 a 4may be coupled to the left knee belt 112 a or the right knee belt 112 bdirectly or indirectly. In the example described above, the one end ofeach of the wires 110 a 1 to 110 a 4 is fixed to, or is directly coupledto, the left knee belt 112 a or the right knee belt 112 b, and the otherend of each of the wires 110 a 1 to 110 a 4 is fixed to, or isindirectly coupled to, the upper-body belt 111 via the corresponding oneof the motors 114. However, each of the wires 110 may be coupled to theupper-body belt 111 and each of the wires 110 may be coupled to the leftknee belt 112 a or the right knee belt 112 b by using the followingconfiguration, for example.

Specifically, the one end of each of the wires 110 may be indirectlycoupled to the left knee belt 112 a or the right knee belt 112 b via thecorresponding one of the motors 114, and the other end of each of thewires 110 may be directly coupled to the upper-body belt 111.Alternatively, both ends of each of the wires 110 may be directlycoupled to the upper-body belt 111 and to the left knee belt 112 a orthe right knee belt 112 b, and a motor, a linear actuator, or apneumatic or hydraulic piston may be disposed in the middle of each ofthe wires 110 to adjust the length of the wire 110.

Alternatively, the one end of each of the wires 110 may be directlycoupled to the left knee belt 112 a or the right knee belt 112 b, andthe other end of each of the wires 110 may be indirectly coupled to theleft knee belt 112 a or the right knee belt 112 b via the correspondingone of the motors 114 in such a manner that each of the wires 110 isarranged to reciprocate between the left knee belt 112 a or the rightknee belt 112 b and the upper-body belt 111. Alternatively, the one endof each of the wires 110 may be directly coupled to the upper-body belt111, and the other end of each of the wires 110 may be indirectlycoupled to the upper-body belt 111 via the corresponding one of themotors 114 in such a manner that each of the wires 110 is arranged toreciprocate between the upper-body belt 111 and the left knee belt 112 aor the right knee belt 112 b.

Alternatively, both ends of each of the wires 110 may be coupled to thecorresponding one of the motors 114 and may be arranged to form a ringthrough the motor 114. In this case, each of the wires 110 is arrangedto reciprocate between the upper-body belt 111 and the left knee belt112 a or the right knee belt 112 b, and each of the motors 114 changesthe length of the circumference of the ring of the corresponding one ofthe wires 110.

In any of the configurations described above, each of the wires 110 iscoupled to the upper-body belt 111 and the left knee belt 112 a or theright knee belt 112 b so that the tension thereof is supported by theupper-body belt 111 and the left knee belt 112 a or the right knee belt112 b. Thus, when each of the motors 114 a 1 to 114 a 4 pulls thecorresponding wire among the wires 110, tension that causes theupper-body belt 111 and the left knee belt 112 a or the right knee belt112 b to come into close proximity to each other is generated in thecorresponding wire.

The force sensors 115 include four force sensors 115 a 1 to 115 a 4. Theforce sensor 115 a 1 detects the tension of the wire 110 a 1 and outputsthe detected tension to the control unit 120. The force sensor 115 a 2detects the tension of the wire 110 a 2 and outputs the detected tensionto the control unit 120. The force sensor 115 a 3 detects the tension ofthe wire 110 a 3 and outputs the detected tension to the control unit120. The force sensor 115 a 4 detects the tension of the wire 110 a 4and outputs the detected tension to the control unit 120. The forcesensor 115 a 1 is disposed on the wire 110 a 1 in the left knee belt 112a. The force sensor 115 a 2 is disposed on the wire 110 a 2 in the leftknee belt 112 a. The force sensor 115 a 3 is disposed on the wire 110 a3 in the right knee belt 112 b. The force sensor 115 a 4 is disposed onthe wire 110 a 4 in the right knee belt 112 b. The force sensors 115 a 1to 115 a 4 may be located in the upper-body belt 111. Each of the forcesensors 115 a 1 to 115 a 4 may be capable of detecting the tension ofthe corresponding wire among the wires 110 a 1 to 110 a 4, and may be astrain gauge force sensor or a piezoelectric force sensor, for example.The force sensors 115 a 1 to 115 a 4 and the wires 110 a 1 to 110 a 4have a one-to-one correspondence.

Each of the wires 110 a 1 to 110 a 4 may be a metallic wire or anon-metallic wire. Examples of the non-metallic wire include a fiberwire and a fiber belt. A fiber wire or fiber belt is made of a materialsuch as polyester fiber, nylon fiber, acrylic fiber, para-aramid fiber,ultrahigh molecular weight polyethylene fiber,poly-p-phenylenebenzobisoxazole (PBO) fiber, polyarylate fiber, orcarbon fiber. In this embodiment, four coupling belts 111 b 1 to 111 b 4are arranged along the wires 110 a 1 to 110 a 4, respectively, and eachof the coupling belts 111 b 1 to 111 b 4 extends from the upper-bodybelt 111 to the left knee belt 112 a or the right knee belt 112 b. Thecoupling belts 111 b 1 to 111 b 4 and the wires 110 a 1 to 110 a 4 havea one-to-one correspondence. As a non-limiting example, the couplingbelts 111 b 1 to 111 b 4 are each integrated with the upper-body belt111 and the left knee belt 112 a or the right knee belt 112 b and aremade of a material similar to that of the belts 111, 112 a, and 112 b.For example, the upper-body belt 111, the knee belts 112 a and 112 b,and the coupling belts 111 b 1 to 111 b 4 may form a single suit havingan assistance function that is wearable by the user 1. Each of thecoupling belts 111 b 1 to 111 b 4 contains and covers the correspondingwire among the wires 110 a 1 to 110 a 4. The coupling belts 111 b 1 to111 b 4 may be collectively referred to as coupling belts 111 b.

The arrangement configuration of the wires 110 a 1 to 110 a 4 will bedescribed in detail with reference to FIG. 1, FIG. 2, and FIG. 4. FIG. 4schematically illustrates the arrangement of the constituent elements ofthe assistance apparatus 100 illustrated in FIG. 1. The wire 110 a 1couples the upper-body belt 111 and the left knee belt 112 a to eachother via the motor 114 a 1 on or above the front part of the body ofthe user 1. The wire 110 a 1 extends upward from the left knee belt 112a on or above the front part of the body of the user 1. The wire 110 a 2couples the upper-body belt 111 and the left knee belt 112 a to eachother via the motor 114 a 2 on or above the back part of the body of theuser 1. The wire 110 a 2 extends upward from the left knee belt 112 a onor above the back part of the body of the user 1. The wire 110 a 3couples the upper-body belt 111 and the right knee belt 112 b to eachother via the motor 114 a 3 on or above the front part of the body ofthe user 1. The wire 110 a 3 extends upward from the right knee belt 112b on or above the front part of the body of the user 1. The wire 110 a 4couples the upper-body belt 111 and the right knee belt 112 b to eachother via the motor 114 a 4 on or above the back part of the body of theuser 1. The wire 110 a 4 extends upward from the right knee belt 112 bon or above the back part of the body of the user 1. In this manner, thewire 110 a 1 is located on or above the front part of the left leg ofthe user 1, the wire 110 a 2 is located on or above the back part of theleft leg of the user 1, the wire 110 a 3 is located on or above thefront part of the right leg of the user 1, and the wire 110 a 4 islocated on or above the back part of the right leg of the user 1. Thewires 110 a 1 to 110 a 4 are pulled individually to apply forces indifferent directions to the left and right legs.

In the example illustrated in FIG. 1, FIG. 2, and FIG. 4, the wires 110a 1 and 110 a 3 do not cross each other on or above the front part ofthe body of the user 1. However, the wires 110 a 1 and 110 a 3 may crosseach other on or above the front part of the body of the user 1. In theexample illustrated in FIG. 1, FIG. 2, and FIG. 4, the wires 110 a 2 and110 a 4 do not cross each other on or above the back part of the body ofthe user 1. However, the wires 110 a 2 and 110 a 4 may cross each otheron or above the back part of the body of the user 1.

The motors 114 a 1 to 114 a 4 pull the wires 110 a 1 to 110 a 4 to applytensions to the wires 110 a 1 to 110 a 4, respectively, and the tensionsare transmitted to the left and right legs of the user 1 via theupper-body belt 111 and the knee belts 112 a and 112 b. To effectivelytransmit the tensions of the wires 110 a 1 to 110 a 4 to the left andright legs of the user 1, the upper-body belt 111 and the knee belts 112a and 112 b may have rigidity so as not to be deformable and haveinflexibility so as not to be extensible. As described above, examplesof the material of the upper-body belt 111 and the knee belts 112 a and112 b include a non-extensible material. The upper-body belt 111 and theknee belts 112 a and 112 b described above are worn by the user 1 insuch a manner as to tightly fit the body of the user 1, thus efficientlytransmitting the driving forces of the motors 114 a 1 to 114 a 4 to thelegs of the user 1 through the wires 110 a 1 to 110 a 4 and effectivelyassisting movements of the legs of the user 1. The term “assisting”, asused herein, is used to include supporting the movement of the user inorder to allow the user to perform a predetermined motion and forcingthe body of the user to perform the predetermined motion to inducemovements of the body.

A further description will be given of a relationship between tensionsapplied to the wires 110 a 1 to 110 a 4 by the assistance apparatus 100and motions of the user that are assisted with the tensions. Forexample, FIG. 5 illustrates example motions of the right leg of theuser, which are assisted by the assistance apparatus 100. In the exampleillustrated in FIG. 5, the assistance apparatus 100 applies anassistance force to the right leg during the swing phase of gait. Theassistance apparatus 100 may apply an assistance force to the right legduring the stance phase of gait. The assistance apparatus 100 alsoenables the left leg of the user to perform motions similar to those ofthe right leg. As illustrated in FIG. 5, the assistance apparatus 100can apply an assistance force for flexion and extension to the hip jointof the right leg of the user. The flexion of the hip joint is a motionof moving the thigh forward, and the extension of the hip joint is amotion of moving the thigh backward.

Further, a relationship between motions of the user, which are induced,or assisted, by the assistance apparatus 100, and assistance forcesgiven to the user through the wires 110 a 1 to 110 a 4 will be describedwith reference to FIG. 6A to FIG. 7B. FIG. 6A illustrates a case wherethe assistance apparatus 100 according to the embodiment assists flexionof the hip joint of the left leg of the user, and FIG. 6B illustrates acase where the assistance apparatus 100 according to the embodimentassists flexion of the hip joint of the right leg of the user. In FIG.6A, to flex the left leg, the control unit 120 drives the motor 114 a 1to increase the tension of the wire 110 a 1, that is, to generate atension in the wire 110 a 1. In FIG. 6B, to flex the right leg, thecontrol unit 120 drives the motor 114 a 3 to increase the tension of thewire 110 a 3. The control unit 120 may control the tensions of the wires110 in accordance with the detection results of the force sensors 115 a1 to 115 a 4 or in accordance with the amount of driving of the motors114 a 1 to 114 a 4. The details of the control unit 120 will bedescribed below.

In this embodiment, as a non-limiting example, a tension is applied toeach of the wires 110 a 1 to 110 a 4 in a normal state before flexion.The tension may be applied so as to prevent the corresponding one of thewires 110 a 1 to 110 a 4 from loosening and may be less than or equal to10 N or less than or equal to 5 N, for example. To flex the left leg andthe right leg, the tensions of the wires 110 a 1 and 110 a 3 are eachincreased to, for example, a value greater than or equal to 40 N andless than or equal to 100 N. An example for the left leg will bedescribed. A tension greater than or equal to 40 N is exerted on thewire 110 a 1 for a user, who is a healthy adult male in 20s to 40s. Atthis time, the user is able to clearly recognize that a force in aflexing direction acts on the left leg and promotes flexion of the leftleg. When a tension over 80 N is exerted on the wire 110 a 1, the leftleg of the user is raised in the flexing direction. When the tensionexerted on the wire 110 a 1 is less than or equal to 20 N, the usercontinues the current motion without substantially perceiving theresistance caused by the tension of the wire 110 a 1. The tension valuesdescribed above are examples. The tension values may be changed, asdesired, in accordance with the age, gender, body size, or physicalactivity level of the user, the type of motion of the leg, the degree ofassistance on the leg, and so on.

FIG. 7A and FIG. 7B illustrate cases where the assistance apparatus 100according to the embodiment assists extension of the hip joints of theleft and right legs of the user, respectively. In FIG. 7A, the controlunit 120 increases the tension of the wire 110 a 2 to extend the leftleg. In FIG. 7B, the control unit 120 increases the tension of the wire110 a 4 to extend the right leg. The tensions of the wires 110 duringextension may be similar to those during flexion.

In the foregoing description, the control unit 120 increases the tensionof one wire to assist one motion of one leg. At this time, the controlunit 120 may control the motors corresponding to the other three wiresin accordance with the motion of the user so that the tensions of theother three wires are kept in the current states, and adjust thetensions of the other three wires. The control unit 120 may control themotors corresponding to the other three wires so as not to exert tensionon the three wires. For example, the control unit 120 may stop theoperation of the motors corresponding to the other three wires.

The assistance apparatus 100 described above is capable of assisting theuser in walking by applying assistance torques, which are assistanceforces in flexing and extending directions, to the user in accordancewith torques generated during the stance phase and swing phase of theleg of the user while the user is walking.

Further, the configuration of the control unit 120 of the assistanceapparatus 100 will be described with reference to FIG. 3. The controlunit 120 controls the overall operation of the assistance apparatus 100.The control unit 120 determines operations to be individually applied tothe wires 110 a 1 to 110 a 4 and controls assistance for the hip jointsof the user 1. The operations to be individually applied to the wires110 a 1 to 110 a 4 are operation patterns of the wires 110 a 1 to 110 a4, including the timings of applying tensions to the wires 110 a 1 to110 a 4, the magnitudes of the tensions, and periods during which thetensions are applied.

The control unit 120 acquires an instruction entered by the user 1 orthe like from an input device 140 included in the assistance apparatus100 or from a terminal device 150 external to the assistance apparatus100, and controls the assistance apparatus 100 to start and stopassistance in accordance with the acquired instruction. The input device140 of the assistance apparatus 100 may be a button, a switch, a key, atouch pad, a microphone of an audio recognition device, or any othersuitable device. The terminal device 150 may be a terminal devicecarried by the user 1 wearing the assistance apparatus 100, and examplesof the terminal device 150 include a smartphone, a smartwatch, a tablet,and a personal computer. The control unit 120 may communicate with theinput device 140 and the terminal device 150 in a wired or wireless way.The wireless communication may be implemented using a wireless localarea network (LAN) such as wireless fidelity (Wi-Fi (registeredtrademark)), or may be short-range wireless communication such asBluetooth (registered trademark) or ZigBee (registered trademark), orany other type of wireless communication. The wired communication may beany existing wired communication. The control unit 120 may include awired or wireless communication circuit. The wired or wirelesscommunication circuit included in the assistance apparatus 100 may beused to perform wired communication or wireless communication. The inputdevice 140 and the terminal device 150 are examples of an interfacedevice.

For example, FIG. 8 illustrates an example input section of the inputdevice 140 included in the assistance apparatus 100 according to theembodiment. The input device 140 includes six physical buttons thataccept input. The six buttons include an “ON” button 141 for startingthe assistance apparatus 100, an “OFF” button 142 for stopping theoperation of the assistance apparatus 100, a normal walking button 143for selecting a normal walking mode, an object transport walking button144 for selecting an object transport walking mode, a “left- handed”button 145 for inputting the “left hand” as the dominant hand of theuser, and a “right-handed” button 146 for inputting the “right hand” asthe dominant hand of the user. The normal walking mode is one of theoperation modes of the assistance apparatus 100. The object transportwalking mode is one of the operation modes of the assistance apparatus100. When the input section of the input device 140 is a touch panel,each button may be implemented as an icon on a screen. The “left-handed”button 145 and the “right-handed” button 146 may be each a dial, a slidebutton, a lever such as a joystick, or any other suitable device. Inthis embodiment, the input device 140 is disposed on the upper-body belt111, as a non-limiting example. Alternatively, the input device 140 maybe disposed on the knee belt 112 a or 112 b or attached to a part of thebody of the user 1, which is away from the upper-body belt 111. Theterminal device 150, which is external to the assistance apparatus 100,may have a button configuration similar to that of the input device 140or an icon configuration on a screen.

In this embodiment, furthermore, as illustrated in FIG. 9, contactsensors 301 a and 301 b and at least one of a pressure-sensitive sensor302 and an inertial measurement unit 303 are attached to the body of theuser 1. FIG. 9 is a diagram illustrating the arrangement of sensors andso on to be attached to the body of the user 1. The contact sensors 301a and 301 b, the pressure-sensitive sensor 302, and the inertialmeasurement unit 303 output detection results to the control unit 120.The contact sensor 301 a is attached to the left hand of the user 1, andthe contact sensor 301 b is attached to the right hand of the user 1.Specifically, the contact sensor 301 a is attached to a finger tip orthe like of a left glove to be worn by the user 1, and the contactsensor 301 b is attached to a finger tip or the like of a right glove tobe worn by the user 1. In this embodiment, as a non-limiting example,the contact sensor 301 a is attached to the forefinger of the left hand,which frequently comes into contact with an object when the user 1 iscarrying the object, and the contact sensor 301 b is attached to theforefinger of the right hand, which frequently comes into contact withan object when the user 1 is carrying the object. The contact sensor 301a and the contact sensor 301 b may be each attached to any other finger,a palm, or the like. The contact sensors 301 a and 301 b detect a directcontact and an indirect contact between the hands of the user 1 and anobject. Examples of the contact sensors 301 a and 301 b include acontact detection sensor, a touch sensor, a proximity sensor, and asensor similar to the pressure-sensitive sensor 302. The contact sensors301 a and 301 b may be attached to the arms of the user 1 or the like,which may come into contact with an object when the user 1 is carryingthe object. The contact sensor 301 a is a left contact sensor attachableto the left hand and is an example of a left pressure sensor. Thecontact sensor 301 b is a right contact sensor attachable to the righthand and is an example of a right pressure sensor.

The left pressure sensor may be a left load sensor or a left forcesensor. The right pressure sensor may be a right load sensor or a rightforce sensor. The left pressure value may be a left pressure valueobtained from the left pressure sensor, a left load value obtained fromthe left load sensor, or a left force value obtained from the left forcesensor. The right pressure value may be a right pressure value obtainedfrom the right pressure sensor, a right load value obtained from theright load sensor, or a right force value obtained from the right forcesensor.

The pressure-sensitive sensor 302 is attached to each of the soles ofthe feet of the user 1. Specifically, the pressure-sensitive sensor 302is attached to each of the bottoms or the like of shoes worn by the user1. The pressure-sensitive sensor 302 may be attached to each of bothfeet of the user 1 or to either foot of the user 1. Thepressure-sensitive sensor 302 detects a pressure acting on each of thesoles of the feet of the user 1, that is, a load. Examples of thepressure-sensitive sensor 302 include a capacitive pressure sensor, apiezoelectric pressure sensor, and a strain gauge pressure sensor. Theinertial measurement unit 303 is attached to a portion of the body ofthe user 1 that moves along with the movement of the user 1, such as thewaist in the upper half of the body of the user 1. Specifically, theinertial measurement unit 303 is attached to the upper-body belt 111.The inertial measurement unit 303 includes an acceleration sensor and agyro sensor (also referred to as an “angular velocity sensor”). Examplesof the acceleration sensor include a three-axis acceleration sensor, andexamples of the gyro sensor include a three-axis gyro sensor. Theinertial measurement unit 303 may include an acceleration sensor, butmay include no gyro sensor. The inertial measurement unit 303 mayfurther include a geomagnetic sensor. The inertial measurement unit 303detects, on the basis of a detected acceleration and angular velocity,the acceleration of the user 1 in each direction, and the movementdirection, movement speed, and movement distance of the user 1. Thepressure-sensitive sensor 302 and the inertial measurement unit 303 areexamples of a gait sensor.

The contact sensors 301 a and 301 b, the pressure-sensitive sensor 302,and the inertial measurement unit 303 exchange information with thecontrol unit 120 via wired communication or wireless communication. Thewired communication may be any of the wired communication describedabove, and the wireless communication may be any of the wirelesscommunication described above.

As illustrated in FIG. 3, the control unit 120 includes a grasprecognition unit 121, a drive control unit 122, a gait timing detectionunit 123, a wire tension recognition unit 124, and a storage unit 125.The grasp recognition unit 121, the drive control unit 122, the gaittiming detection unit 123, and the wire tension recognition unit 124,which are constituent elements of the control unit 120, may beimplemented by a computer system including a processor such as a centralprocessing unit (CPU) or a digital signal processor (DSP) and a memorysuch as a random access memory (RAM) and a read-only memory (ROM). Someor all of the functions of the constituent elements described above maybe achieved by the CPU or the DSP executing a program recorded on theROM by using the RAM as a work memory. Alternatively, some or all of thefunctions of the constituent elements described above may be achieved bya dedicated hardware circuit such as an electronic circuit or anintegrated circuit. The functions of some or all of the constituentelements described above may be implemented by a combination of thesoftware functions described above and a hardware circuit. The programmay be provided as an application by communication via a communicationnetwork such as the Internet, communication conforming to a mobilecommunication standard, communication via any other wireless or wirednetwork, broadcasting, or the like. A computer system and/or a hardwarecircuit constituted by the control unit 120 may be mounted on theupper-body belt 111, accommodated in the containers 111 a 1 to 111 a 4together with the motors 114 a 1 to 114 a 4, or embedded in theupper-body belt 111 at a different location from the motors 114 a 1 to114 a 4, for example. The control unit 120 is an example of a controlcircuit.

The storage unit 125 is capable of storing information, and the storedinformation is retrievable from the storage unit 125. The storage unit125 stores computer programs in accordance with which the constituentelements of the control unit 120 execute processes, threshold valuesdescribed below, input profiles of wire tensions described below, and soon. The storage unit 125 is implemented as a storage device, forexample, a semiconductor memory such as a ROM, a RAM, or a flash memory,a hard disk drive, or a solid state drive (SSD). In this embodiment, thestorage unit 125 is included in the control unit 120. Alternatively, thestorage unit 125 may be disposed separately from the control unit 120.The storage unit 125 is an example of a memory.

The grasp recognition unit 121 detects a load applied to the hand of theuser 1 and detects a grasp of an object by the user 1 accordingly. Thegrasp recognition unit 121 detects loads applied to the left and righthands of the user 1 on the basis of amounts of changes in the sensorvalues acquired from the contact sensors 301 a and 301 b, respectively.The loads detected from the sensor values of the contact sensors 301 aand 301 b are examples of a pressure value. For example, as illustratedin FIG. 10A, the left contact sensor 301 a is placed on the left hand ofthe user 1, and the right contact sensor 301 b is placed on the righthand of the user 1. Specifically, the left contact sensor 301 a isattached to the tip of the forefinger of the left hand, and the rightcontact sensor 301 b is attached to the tip of the forefinger of theright hand. FIG. 10A is a diagram illustrating a relationship betweenthe contact sensors 301 a and 301 b and the hands of the user.

When the contact sensors 301 a and 301 b are piezoelectric sensors, thegrasp recognition unit 121 detects a time point at which each of voltagevalues corresponding to sensor values detected by the contact sensors301 a and 301 b becomes less than a predetermined value, as a time pointat which the corresponding one of the left and right hands of the user 1touches an object, that is, a time point at which the corresponding oneof the left and right hands of the user 1 grasps the object. As each ofthe voltage values of the contact sensors 301 a and 301 b decreases, theload applied by the object to the corresponding one of the left andright hands of the user 1 increases. Accordingly, the grasp recognitionunit 121 calculates the loads applied to the left and right hands of theuser 1 from the voltage values of the contact sensors 301 a and 301 b,respectively. For example, in example signals of the contact sensors 301a and 301 b illustrated in FIG. 10B, the predetermined value isrepresented by “VA”. In FIG. 10B, when the voltage values of the contactsensors 301 a and 301 b remain less than the predetermined value VA,that is, when the user 1 is carrying an object, a voltage value VL ofthe left contact sensor 301 ais smaller than a voltage value VR of theright contact sensor 301 b. Thus, a load LL applied to the left hand ofthe user 1 is larger than a load LR applied to the right hand. The grasprecognition unit 121 calculates the load LL applied to the left hand ofthe user 1 and the load LR applied to the right hand of the user 1 fromthe voltage values VL and VR of the contact sensors 301 a and 301 b,respectively, and outputs the loads LL and LR to the drive control unit122. In the example illustrated in FIG. 10B, VL<VR and LL>LR hold.

The gait timing detection unit 123 detects a gait timing to determine atiming of assisting the user 1. The gait timing may include a timing ofstarting assisting the user 1 during walking, and a timing ofdetermining phases such as a stance phase and a swing phase in a periodduring which the user 1 takes one step. The drive control unit 122determines a timing of assisting the user 1 from the gait timingdetected by the gait timing detection unit 123 and controls theoperation of the motors 114.

Specifically, the gait timing detection unit 123 estimates a gait cycleof the user 1 wearing the assistance apparatus 100, predicts gait phasesin the next one step on the basis of the estimation result, and outputsassistance timings based on the predicted gait phases to the drivecontrol unit 122. A gait cycle is a time interval from heel strike ofone leg to the next heel strike of the same leg. The gait cycle isconstituted by a period of a stance phase and a period of a swing phase.The gait cycle may be sequence of motions occurring from heel strike ofone leg to the next heel strike of the same leg.

The gait timing detection unit 123 detects a timing of heel strike ofthe user 1 on the basis of a sensor value acquired from thepressure-sensitive sensor 302 or on the basis of sensor values acquiredfrom the acceleration sensor and the gyro sensor of the inertialmeasurement unit 303, and estimates a gait phase for each step, or agait cycle, of the user 1 in real time. The gait cycles and the stepsmay be in a one-to-one relationship. Each step of the user 1 is a stepwith either of the left and right legs. For example, each step of theuser 1 corresponds to a period from when the left leg touches the groundto when the left leg touches the ground again. The gait timing detectionunit 123 predicts, based on the estimated gait cycle, a gait phase forthe next step and a starting time and duration of each of the stancephase and swing phase for the next step, and outputs the predictionresults to the drive control unit 122. When the terminal device 150carried by the user 1 includes an inertial measurement unit, the gaittiming detection unit 123 may acquire a sensor value of an accelerationsensor and a sensor value of a gyro sensor from the terminal device 150.

Gait phases represent temporal timings of gait states during a singlestep taken by the user 1. A time point at which one leg of the user 1touches the ground corresponds to a time point at which a gait phase is0%, and a time point at which the same leg of the user 1 touches theground again corresponds to a time point at which a gait phase is 100%.In a gait phase, timings of gait states of the user 1 are represented inthe range of 0% to 100%. For example, a value of 0% to 100% of a gaitphase may correspond to the time elapsed from when one leg of the user 1touches the ground to when the same leg of the user 1 touches the groundagain. Specifically, when the time period from when one leg of the user1 touches the ground to when the same leg of the user 1 touches theground again is 1 second, the gait phase at the point in time at which aperiod of 0.5 seconds elapses from the time when the leg of the user 1touches the ground is represented by 50%.

More specifically, the gait timing detection unit 123 determines a timepoint at which the leg of the user 1 touches the ground on the basis ofthe sensor value of the pressure-sensitive sensor 302 in such a mannerthat, for example, as illustrated in FIG. 11, a time point at which thevoltage value corresponding to the pressure sensor value of thepressure-sensitive sensor 302 becomes less than a predetermined value isdetected as a timing of heel strike. FIG. 11 illustrates an example of asignal based on signals of the pressure-sensitive sensors 302. Forexample, the predetermined value is represented by “VB” in FIG. 11. Aperiod during which the pressure-sensitive sensor 302 measures apressure value greater than or equal to the predetermined valuecorresponds to a period of heel contact. The pressure-sensitive sensor302 is placed at each of the feet of the user 1. The gait timingdetection unit 123 acquires a timing at which the shoe touches theground using the pressure-sensitive sensor 302, rather than a timingthat is based on the inertial measurement unit 303 located in theupper-body belt 111 or the like. Thus, the gait timing detection unit123 can more reliably estimate a gait cycle.

When the inertial measurement unit 303 is used, the gait timingdetection unit 123 determines a time point at which the foot of the user1 touches the ground on the basis of information obtained by theacceleration sensor. For a method for estimating a time point at which afoot touches the ground by using an acceleration sensor, see, forexample, IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, VOL. 52, NO. 3,2005, p. 488, FIG. 1, p. 489, FIG. 2. When estimating a gait cycle onthe basis of a sensor value of the inertial measurement unit 303, thegait timing detection unit 123 may estimate a gait cycle by using signalwaveforms obtained from the acceleration sensor and the gyro sensor. Forexample, a gait cycle can be estimated by using a signal waveformobtained from the acceleration sensor, as illustrated in FIG. 12. In theexample illustrated in FIG. 12, the signal waveform obtained from theacceleration sensor can be used to estimate a time point at which thefoot of the user 1 touches the ground, and a gait cycle can be estimatedaccordingly. FIG. 12 illustrates an example of a signal of theacceleration sensor of the inertial measurement unit 303.

The user 1 may wear an angle sensor (also referred to as a “tiltsensor”). In this case, the angle sensor is attached to, for example, athigh of the user 1. The gait timing detection unit 123 acquires theangle of the hip joint of the user 1 as gait information. The gaittiming detection unit 123 calculates a gait phase on the basis of acycle of change in the angle of the hip joint of the user 1.

Regardless of which of the pressure-sensitive sensor 302 and theinertial measurement unit 303 is used, for example, the gait timingdetection unit 123 may estimate, based on a sensor value of thepressure-sensitive sensor 302 or a sensor value of the inertialmeasurement unit 303 for the latest three steps of the user 1, anelapsed time of 0% to 100% of a gait phase for each step and maycalculate an average value of the three elapsed times. Then, the gaittiming detection unit 123 may predict the point in time corresponding to100% of the gait phase for the next step on the basis of the averagevalue of the elapsed times. Further, the gait timing detection unit 123may estimate the start timings of the stance phase and the swing phaseduring the gait phase for each step on the basis of the signal waveformof the sensor and calculate an average value of the start timings forthe three steps. Then, the gait timing detection unit 123 may predict,based on the average value, the start timings of the stance phase andthe swing phase for the next one step.

Alternatively, the gait timing detection unit 123 may estimate, based ona sensor value of the pressure-sensitive sensor 302 or a sensor value ofthe inertial measurement unit 303 for the last one step of the user 1,an elapsed time of 0% to 100% of the gait phase for the one step and maypredict the point in time corresponding to 100% of the gait phase forthe next step on the basis of the estimated elapsed time. Further, thegait timing detection unit 123 may estimate the start timings of thestance phase and the swing phase during the one step on the basis of thesensor values for the last one step of the user 1, and may predict thestart timings of the stance phase and the swing phase for the next onestep.

The wire tension recognition unit 124 detects the tensions generated inthe wires 110 a 1 to 110 a 4. The wire tension recognition unit 124detects the tensions of the wires 110 a 1 to 110 a 4 on the basis ofsensor values acquired from the force sensors 115 a 1 to 115 a 4. Thewire tension recognition unit 124 outputs the detected tensions of thewires 110 a 1 to 110 a 4 to the drive control unit 122.

The drive control unit 122 controls the motors 114 a 1 to 114 a 4, whichrespectively adjust the tensions of the wires 110 a 1 to 110 a 4, on thebasis of information on a predicted gait phase of the user 1, which isacquired from the gait timing detection unit 123, and on the basis ofinformation indicating whether the user 1 is carrying an object, whichis acquired from the grasp recognition unit 121. The drive control unit122 starts the motors 114 a 1 to 114 a 4, stops the operation of themotors 114 a 1 to 114 a 4, and controls the amount by which the wires110 a 1 to 110 a 4 are respectively pulled by the motors 114 a 1 to 114a 4 and the pulling tensions of the wires 110 a 1 to 110 a 4. The drivecontrol unit 122 controls the amount of rotation of each of the motors114 a 1 to 114 a 4 and adjusts the rotation torque of each of the motors114 a 1 to 114 a 4, thereby enabling control of the amount by which thecorresponding wire among the wires 110 is pulled and the pullingtensions of the corresponding wire.

Specifically, the drive control unit 122 determines a type of assistanceto be provided to the user 1 on the basis of the prediction result ofthe gait timing acquired from the gait timing detection unit 123.Examples of the type of assistance include motions of the leg on whichassistance is to be provided to the user 1, such as flexion andextension. In accordance with the type of assistance, the drive controlunit 122 further determines a wire to be pulled to assist a motion ofthe user 1 among the wires 110 a 1 to 110 a 4, a tension to be appliedto the wire, and a timing of pulling the wire.

Further, the drive control unit 122 changes the relationship between thetension of a wire and the timing of pulling the wire even for the sametype of assistance on the basis of information acquired from the grasprecognition unit 121 indicating whether the user 1 is carrying anobject, the loads applied to the left and right hands of the user 1, andso on.

An assistance correspondence, which is a relationship between the gaittiming acquired from the gait timing detection unit 123 and the type ofassistance, is set in advance and is stored in, for example, the storageunit 125. A wire-tension relationship, which is a relationship between awire to be pulled, a tension of the wire, and a timing of pulling thewire, is set in advance in accordance with the type of assistance,information indicating whether the user 1 is carrying an object, and soon, and is stored in, for example, the storage unit 125. Thewire-tension relationship may be updated on the basis of the achievementof assistance-based control by the assistance apparatus 100. On thebasis of information on the assistance correspondence and thewire-tension relationship, which are stored in the storage unit 125, thedrive control unit 122 determines a type of assistance to be provided tothe user 1 and determines control of wires corresponding to thedetermined type of assistance. The drive control unit 122 controls themotors linked to the determined wires, in accordance with tensions to beapplied to the wires and timings of puling the wires.

Further, the drive control unit 122 controls the operation of the motors114 a 1 to 114 a 4 on the basis of information on the tensions of thewires 110 a 1 to 110 a 4, which is acquired from the wire tensionrecognition unit 124, so that the tensions of the wires 110 a 1 to 110 a4 have predetermined levels. In addition, the drive control unit 122 maychange the wire-tension relationship on the basis of, in addition to theinformation acquired from the grasp recognition unit 121, the gaittiming detection unit 123, and the wire tension recognition unit 124,information on the user 1, such as age, gender, body size, and physicalactivity level, the degree of assistance on the leg, and so on, and mayuse the changed wire-tension relationship.

2. Modification of Assistance Apparatus

In the assistance apparatus 100 described above, the upper-body belt 111is coupled to the knee belts 112 a and 112 b by using the four wires 110a 1 to 110 a 4. However, the number of wires is not limited to that inthe embodiment. For example, as illustrated in FIG. 13 to FIG. 17, eightwires may be used. FIG. 13 is a perspective view of a user 1 wearing anassistance apparatus 200 according to a modification of the embodiment,as viewed obliquely from the front. FIG. 14 is a front view of the user1 wearing the assistance apparatus 200 illustrated in FIG. 13. FIG. 15is a back view of the user 1 wearing the assistance apparatus 200illustrated in FIG. 13. FIG. 16 is a diagram schematically illustratingthe arrangement of constituent elements of the assistance apparatus 200illustrated in FIG. 13. FIG. 17 is a block diagram illustrating afunctional configuration of the assistance apparatus 200 illustrated inFIG. 13.

As illustrated in FIG. 13 to FIG. 17, the assistance apparatus 200according to the modification includes an upper-body belt 111, kneebelts 112 a and 112 b, and eight wires, namely, first to eighth wires110 a 1 to 110 a 8. The assistance apparatus 200 further includes amotor 114 a 1 linked to the first wire 110 a 1, a motor 114 a 2 linkedto the second wire 110 a 2, a motor 114 a 3 linked to the third wire 110a 3, a motor 114 a 4 linked to the fourth wire 110 a 4, a motor 114 a 5linked to the fifth wire 110 a 5, a motor 114 a 6 linked to the sixthwire 110 a 6, a motor 114 a 7 linked to the seventh wire 110 a 7, amotor 114 a 8 linked to the eighth wire 110 a 8, a force sensor 115 a 1disposed on the first wire 110 a 1, a force sensor 115 a 2 disposed onthe second wire 110 a 2, a force sensor 115 a 3 disposed on the thirdwire 110 a 3, a force sensor 115 a 4 disposed on the fourth wire 110 a4, a force sensor 115 a 5 disposed on the fifth wire 110 a 5, a forcesensor 115 a 6 disposed on the sixth wire 110 a 6, a force sensor 115 a7 disposed on the seventh wire 110 a 7, a force sensor 115 a 8 disposedon the eighth wire 110 a 8, and a control unit 120.

The upper-body belt 111 includes containers 111 a 1, 111 a 2, 111 a 3,and 111 a 4 so as to correspond to the front part, left side part, backpart, and right side part of the body of the user 1, respectively. Themotors 114 a 1 and 114 a 3 are accommodated in the container 111 a 1,the motors 114 a 5 and 114 a 6 are accommodated in the container 111 a2, the motors 114 a 2 and 114 a 4 are accommodated in the container 111a 3, and the motors 114 a 7 and 114 a 8 are accommodated in thecontainer 111 a 4.

The first wire 110 a 1 and the fifth wire 110 a 5 are arranged to extendin directions crossing each other on or above the front part of the bodyof the user 1, and, more specifically, are arranged to cross each other.Each of the first wire 110 a 1 and the fifth wire 110 a 5 has one endfixed to the left knee belt 112 a. The first wire 110 a 1 has anotherend coupled to the motor 114 a 1, and the fifth wire 110 a 5 has anotherend coupled to the motor 114 a 5. That is, the first wire 110 a 1couples the left knee belt 112 a and the motor 114 a 1 to each other,and the fifth wire 110 a 5 couples the left knee belt 112 a and themotor 114 a 5 to each other.

The second wire 110 a 2 and the sixth wire 110 a 6 are arranged toextend in directions crossing each other on or above the back part ofthe body of the user 1, and, more specifically, are arranged to crosseach other. Each of the second wire 110 a 2 and the sixth wire 110 a 6has one end fixed to the left knee belt 112 a. The second wire 110 a 2has another end coupled to the motor 114 a 2, and the sixth wire 110 a 6has another end coupled to the motor 114 a 6. That is, the second wire110 a 2 couples the left knee belt 112 a and the motor 114 a 2 to eachother, and the sixth wire 110 a 6 couples the left knee belt 112 a andthe motor 114 a 6 to each other.

The third wire 110 a 3 and the seventh wire 110 a 7 are arranged toextend in directions crossing each other on or above the front part ofthe body of the user 1, and, more specifically, are arranged to crosseach other. Each of the third wire 110 a 3 and the seventh wire 110 a 7has one end fixed to the right knee belt 112 b. The third wire 110 a 3has another end coupled to the motor 114 a 3, and the seventh wire 110 a7 has another end coupled to the motor 114 a 7. That is, the third wire110 a 3 couples the right knee belt 112 b and the motor 114 a 3 to eachother, and the seventh wire 110 a 7 couples the right knee belt 112 band the motor 114 a 7 to each other.

The fourth wire 110 a 4 and the eighth wire 110 a 8 are arranged toextend in directions crossing each other on or above the back part ofthe body of the user 1, and, more specifically, are arranged to crosseach other. Each of the fourth wire 110 a 4 and the eighth wire 110 a 8has one end fixed to the right knee belt 112 b. The fourth wire 110 a 4has another end coupled to the motor 114 a 4, and the eighth wire 110 a8 has another end coupled to the motor 114 a 8. That is, the fourth wire110 a 4 couples the right knee belt 112 b and the motor 114 a 4 to eachother, and the eighth wire 110 a 8 couples the right knee belt 112 b andthe motor 114 a 8 to each other.

Further, the first wire 110 a 1 and the second wire 110 a 2 extendupward and toward the right side of the body of the user 1 from the leftknee belt 112 a. Specifically, the first wire 110 a 1 and the secondwire 110 a 2 extend to the right side of the body of the user 1 whileextending upward from the left knee belt 112 a, and, for example, extendupward and diagonally to the right from the left knee belt 112 a. Thefifth wire 110 a 5 and the sixth wire 110 a 6 extend upward and towardthe left side of the body of the user 1 from the left knee belt 112 a.Specifically, the fifth wire 110 a 5 and the sixth wire 110 a 6 extendto the left side of the body of the user 1 while extending upward fromthe left knee belt 112 a, and, for example, extend upward and diagonallyto the left from the left knee belt 112 a. The third wire 110 a 3 andthe fourth wire 110 a 4 extend upward and toward the left side of thebody of the user 1 from the right knee belt 112 b. Specifically, thethird wire 110 a 3 and the fourth wire 110 a 4 extend to the left sideof the body of the user 1 while extending upward from the right kneebelt 112 b, and, for example, extend upward and diagonally to the leftfrom the right knee belt 112 b. The seventh wire 110 a 7 and the eighthwire 110 a 8 extend upward and toward the right side of the body of theuser 1 from the right knee belt 112 b. Specifically, the seventh wire110 a 7 and the eighth wire 110 a 8 extend to the right side of the bodyof the user 1 while extending upward from the right knee belt 112 b,and, for example, extend upward and diagonally to the right from theright knee belt 112 b.

Extending of two wires in directions crossing each other is equivalentto crossing of directions in which the two wires extend. Further,crossing of directions in which the two wires extend is equivalent toextending of the two wires in directions that are not parallel to eachother. The directions may cross each other at an intersection, or mayhave no intersection therebetween and may not cross each other. Thus,the two wires may actually cross each other at an intersection or maynot actually cross each other. Such two wires extending in directionscrossing each other may or may not cross each other when the user 1 isviewed from outside the user 1. When the two wires do not cross eachother, as illustrated in FIG. 18 and FIG. 19, the two wires may extendto form a V shape, for example, or may extend away from each other. FIG.18 and FIG. 19 illustrate modifications of the arrangement of the wires110 in the assistance apparatus 200 illustrated in FIG. 13.

In this modification, furthermore, eight coupling belts 111 b 1 to 111 b8 are arranged along the first wire 110 a 1 to the eighth wire 110 a 8,respectively, and each of the eight coupling belts 111 b 1 to 111 b 8extends from the upper-body belt 111 to the left knee belt 112 a or theright knee belt 112 b. The coupling belts 111 b 1 to 111 b 8 and thefirst wire 110 a 1 to the eighth wire 110 a 8 have a one-to-onecorrespondence.

In this modification, as a non-limiting example of pairs of two wiresextending in directions crossing each other, two wires in each pair ofwires cross each other to form an X shape. The first wire 110 a 1 to theeighth wire 110 a 8 may have any other arrangement configuration. Asillustrated in FIG. 18, for example, the first wire 110 a 1 and thefifth wire 110 a 5 may be arranged to form a V shape. In this case, thefirst wire 110 a 1 and the fifth wire 110 a 5 may form a tapered shapethat becomes wider toward the top from the left knee belt 112 a. Inaddition, on the left knee belt 112 a, the first wire 110 a 1 and thefifth wire 110 a 5 may be arranged in close proximity to each other inthe manner illustrated in FIG. 18 or may be arranged away from eachother in the manner illustrated in FIG. 19. The same applies to theother pairs of wires.

Alternatively, as illustrated in FIG. 20, for example, the first wire110 a 1 and the fifth wire 110 a 5 may be arranged to form an inverted Vshape. In this case, the first wire 110 a 1 and the fifth wire 110 a 5may form a tapered shape that becomes narrower toward the top from theleft knee belt 112 a. In addition, on the upper-body belt 111, the firstwire 110 a 1 and the fifth wire 110 a 5 may be arranged in closeproximity to each other in the manner illustrated in FIG. 20 may bearranged away from each other in the manner illustrated in FIG. 21. Thesame applies to the other pairs of wires. FIG. 20 and FIG. 21 illustratemodifications of the arrangement of the wires 110 in the assistanceapparatus 200 illustrated in FIG. 13.

In FIG. 13 to FIG. 15, the first wire 110 a 1 and the third wire 110 a 3extending from the container 111 a 1 form an inverted V shape, the fifthwire 110 a 5 and the sixth wire 110 a 6 extending from the container 111a 2 form an inverted V shape, the second wire 110 a 2 and the fourthwire 110 a 4 extending from the container 111 a 3 form an inverted Vshape, and the seventh wire 110 a 7 and the eighth wire 110 a 8extending from the container 111 a 4 form an inverted V shape. However,the arrangement of the first wire 110 a 1 to the eighth wire 110 a 8 onthe upper-body belt 111 is not limited to the arrangement describedabove. For example, a wound portion of the first wire 110 a 1 and awound portion of the third wire 110 a 3 may be arranged away from eachother so that the two wires 110 a 1 and 110 a 3 do not cross each otheror may be arranged so that the two wires 110 a 1 and 110 a 3 cross eachother to form an X shape. A wound portion of the fifth wire 110 a 5 anda wound portion of the sixth wire 110 a 6 may be arranged away from eachother so that the two wires 110 a 5 and 110 a 6 do not cross each otheror may be arranged so that the two wires 110 a 5 and 110 a 6 cross eachother to form an X shape. A wound portion of the second wire 110 a 2 anda wound portion of the fourth wire 110 a 4 may be arranged away fromeach other so that the two wires 110 a 2 and 110 a 4 do not cross eachother or may be arranged so that the two wires 110 a 2 and 110 a 4 crosseach other to form an X shape. A wound portion of the seventh wire 110 a7 and a wound portion of the eighth wire 110 a 8 may be arranged awayfrom each other so that the two wires 110 a 7 and 110 a 8 do not crosseach other or may be arranged so that the two wires 110 a 7 and 110 a 8cross each other to form an X shape.

In the assistance apparatus 200 described above, for example, the motor114 a 1 generates a tension in the first wire 110 a 1, and the motor 114a 5 generates a tension in the fifth wire 110 a 5. The assistanceapparatus 200 drives the motor 114 a 1 to increase the tension of thefirst wire 110 a 1. Thus, a force is exerted on the leg of the user 1 ina direction in which the distance between the knee and the heel isreduced to assist a motion of the ankle of the user 1 during walking.The assistance apparatus 200 drives the motor 114 a 5 to increase thetension of the fifth wire 110 a 5. Thus, a force is exerted on the legof the user 1 in a direction in which the distance between the knee andthe heel is reduced to assist a motion of the ankle of the user 1 duringwalking. Further, by setting the tensions of the first wire 110 a 1 andthe fifth wire 110 a 5 to different values, the assistance apparatus 200can generate a moment of force regarding a left or right tilt of theheel of the user 1 and can assist a motion of the ankle of the user 1during walking.

The assistance apparatus 200 can apply an assistance force to the hipjoint of the left leg and the hip joint of the right leg of the user 1to flex and extend the hip joints. Referring to FIG. 22A, a case isillustrated in which the assistance apparatus 200 according to themodification assists flexion of the hip joint of the left leg of theuser 1. Referring to FIG. 22B, a case is illustrated in which theassistance apparatus 200 according to the modification assists flexionof the hip joint of the right leg of the user 1. In FIG. 22A, to flexthe left leg, the drive control unit 122 drives the motors 114 a 1 and114 a 5 to increase the tensions of the first wire 110 a 1 and the fifthwire 110 a 5. In FIG. 22B, to flex the right leg, the drive control unit122 drives the motors 114 a 3 and 114 a 7 to increase the tensions ofthe third wire 110 a 3 and the seventh wire 110 a 7. In thismodification, the tensions of the first wire 110 a 1 and the fifth wire110 a 5 are assumed to be equivalent, but may be different. In thismodification, the tensions of the third wire 110 a 3 and the seventhwire 110 a 7 are assumed to be equivalent, but may be different.

Referring to FIG. 23A, a case is illustrated in which the assistanceapparatus 200 according to the modification assists extension of the hipjoint of the left leg of the user 1. Referring to FIG. 23B, a case isillustrated in which the assistance apparatus 200 according to themodification assists extension of the hip joint of the right leg of theuser 1. In FIG. 23A, to extend the left leg, the drive control unit 122increases the tensions of the second wire 110 a 2 and the sixth wire 110a 6. In FIG. 23B, to extend the right leg, the drive control unit 122increases the tensions of the fourth wire 110 a 4 and the eighth wire110 a 8. The tension of the second wire 110 a 2 for extension may besimilar to the tension of the first wire 110 a 1 for flexion. Thetension of the sixth wire 110 a 6 for extension may be similar to thetension of the fifth wire 110 a 5 for flexion. The tension of the fourthwire 110 a 4 for extension may be similar to the tension of the thirdwire 110 a 3 for flexion. The tension of the eighth wire 110 a 8 forextension may be similar to the tension of the seventh wire 110 a 7 forflexion.

In the foregoing description, the drive control unit 122 increases thetensions of two wires among the wires 110 to assist one motion of oneleg. In this case, the drive control unit 122 may control the motors 114to adjust the tensions of the wires 110 in accordance with a motion ofthe user 1 while keeping the tensions of the other six wires at thecurrent value, or may stop the motors corresponding to the six wires soas not to exert the tensions on the six wires.

3. Operation of Assistance Apparatus

-   3-1. Overall Operation of Assistance Apparatus

Next, the overall operation flow of an assistance apparatus will bedescribed. Since the assistance apparatus 100 according to theembodiment and the assistance apparatus 200 according to themodification are similar in terms of the overall operation flow of anassistance apparatus, the operation of the assistance apparatus 100according to the embodiment will be described, with no description givenof the operation of the assistance apparatus 200 according to themodification. FIG. 24 is a flowchart illustrating the overall flow of anoperation of the assistance apparatus 100 for assisting the user 1.

As illustrated in FIG. 3 and FIG. 24, in step S001, the control unit 120of the assistance apparatus 100 acquires, or receives, an instructionfor an operation mode from the user 1. The control unit 120 determinesthe operation mode of the assistance apparatus 100 in accordance withthe acquired instruction. Specifically, the drive control unit 122 ofthe control unit 120 receives an instruction for an operation mode to beimplemented by the assistance apparatus 100 from the input device 140 ofthe assistance apparatus 100 or from the terminal device 150. Examplesof the operation mode include the normal walking mode, in which a userwalks without an object such as an item like luggage, and the objecttransport walking mode, in which, a user walks with an object.

In step S002, the drive control unit 122 determines whether theinstruction indicates the object transport walking mode. If theinstruction indicates the object transport walking mode (Yes in stepS002), the drive control unit 122 proceeds to step S003. If theinstruction does not indicate the object transport walking mode (No instep S002), the drive control unit 122 proceeds to step S009.

In step S003, the grasp recognition unit 121 of the control unit 120determines whether the user 1 is carrying an object. The grasprecognition unit 121 detects whether the user 1 is carrying an object onthe basis of the sensor values acquired from the contact sensors 301 aand 301 b that the user 1 wears on their hands, and outputs a detectionresult to the drive control unit 122. If the grasp recognition unit 121determines that the user 1 is carrying an object (Yes in step S003), theprocess proceeds to step S004. If the grasp recognition unit 121determines that the user 1 is carrying no object (No in step S003), theprocess proceeds to step S007.

In step S004, the drive control unit 122 acquires a gait phase predictedby the gait timing detection unit 123. Further, in step S005, the drivecontrol unit 122 controls the motors 114 a 1 to 114 a 4 on the basis ofthe acquired gait phase to generate tensions in the wires 110 a 1 to 110a 4 of the assistance apparatus 100 in accordance with preset inputprofiles for assisting the user 1 in walking. The preset input profilesare stored in the storage unit 125. By generating tensions in the wires110 a 1 to 110 a 4, the drive control unit 122 assists flexion andextension of the left and right legs of the user 1. At this time, thedrive control unit 122 controls the tension of the wire 110 a 1 on thebasis of the tension of the wire 110 a 1, which is acquired from theforce sensor 115 a 1, controls the tension of the wire 110 a 2 on thebasis of the tension of the wire 110 a 2, which is acquired from theforce sensor 115 a 2, controls the tension of the wire 110 a 3 on thebasis of the tension of the wire 110 a 3, which is acquired from theforce sensor 115 a 3, and controls the tension of the wire 110 a 4 onthe basis of the tension of the wire 110 a 4, which is acquired from theforce sensor 115 a 4.

Further, the drive control unit 122 changes the balance, or ratio, oftensions to be generated in the wires 110 a 1 to 110 a 4, on the basisof a detection result of the grasp recognition unit 121. Then, the drivecontrol unit 122 generates tensions in the wires 110 a 1 to 110 a 4 inaccordance with input profiles in which the ratio has been changed. Theinput profiles in which the ratio has been changed may be stored in thestorage unit 125 or may be calculated by the drive control unit 122.

For example, if the loads applied to the left and right hands of theuser 1, which are detected by the grasp recognition unit 121, are equal,the drive control unit 122 makes the tension to be generated in the wire110 a 1 equal to the tension to be generated in the wire 110 a 3, makesthe tension to be generated in the wire 110 a 1 equal to the tension tobe generated in the wire 110 a 4, makes the tension to be generated inthe wire 110 a 2 equal to the tension to be generated in the wire 110 a3, and makes the tension to be generated in the wire 110 a 2 equal tothe tension to be generated in the wire 110 a 4. If the loads applied tothe left and right hands of the user 1 are different, the drive controlunit 122 makes the tension to be generated in the wire 110 a 1 differentfrom the tension to be generated in the wire 110 a 3, makes the tensionto be generated in the wire 110 a 1 different from the tension to begenerated in the wire 110 a 4, makes the tension to be generated in thewire 110 a 2 different from the tension to be generated in the wire 110a 3, or makes the tension to be generated in the wire 110 a 2 differentfrom the tension to be generated in the wire 110 a 4. In this way, theassistance apparatus 100 assists a user in walking while carrying anobject on the basis of loads applied to the left and right hands of theuser. The expression “two loads being equal” is used to include not onlya state in which the two loads are the same but also a state in whichthe difference between the two loads is within a range of several to tenor so percent (%).

Each input profile includes a timing at which a tension is generated ina wire during a gait cycle of the left leg, a period during which atension is generated in the wire, the value of the tension of the wireduring the period, a timing at which a tension is generated in a wireduring a gait cycle of the right leg, a period during which a tension isgenerated in the wire, and the value of the tension of the wire duringthe period. The input profiles are set in advance and are stored in thestorage unit 125. While receiving assistance provided by the assistanceapparatus 100, the user 1 may adjust the timing of generation of a wiretension, the period of generation of the wire tension, and the value ofthe wire tension via the input device 140 or the terminal device 150.The drive control unit 122 may reflect the adjustment results to changethe input profile, and may store the changed input profile in thestorage unit 125. The drive control unit 122 may control the wiretension by using the changed input profile.

Then, in step S006, the drive control unit 122 determines whether a stopinstruction for stopping assistance provided by the assistance apparatus100 has been acquired from the user 1. If the stop instruction has beenacquired (Yes in step S006), the drive control unit 122 stops theoperation of the assistance apparatus 100 and terminates the series ofprocesses. If no stop instruction is acquired (No in step S006), theprocess returns to step S003. The stop instruction may be an instructionfor changing the operation mode.

By repeatedly performing the operations of steps S003 to S006, the drivecontrol unit 122 controls wire tensions by using input profiles in whichthe balance of the tensions to be generated in the wires 110 a 1 to 110a 4 has been changed in accordance with a difference between the loadsapplied to the left and right hands of the user 1 and so on. Thus, evenif the relationship between the loads applied to the left and righthands is changed, the drive control unit 122 controls wire tensions inaccordance with the changed relationship.

In step S007, the drive control unit 122 acquires a gait phase predictedby the gait timing detection unit 123. Further, in step S008, the drivecontrol unit 122 controls the motors 114 a 1 to 114 a 4 on the basis ofthe acquired gait phase to generate tensions in the wires 110 a 1 to 110a 4 in accordance with preset input profiles for assisting the user 1 inwalking. The drive control unit 122 controls the tension of the wire 110a 1 on the basis of the tension of the wire 110 a 1, which is acquiredfrom the force sensor 115 a 1, controls the tension of the wire 110 a 2on the basis of the tension of the wire 110 a 2, which is acquired fromthe force sensor 115 a 2, controls the tension of the wire 110 a 3 onthe basis of the tension of the wire 110 a 3, which is acquired from theforce sensor 115 a 3, and controls the tension of the wire 110 a 4 onthe basis of the tension of the wire 110 a 4, which is acquired from theforce sensor 115 a 4, to assist flexion and extension of the left andright legs of the user 1. In addition, the drive control unit 122 doesnot acquire the loads applied to the left and right hands of the user 1from the grasp recognition unit 121 and thus controls the tensions ofthe wires 110 a 1 to 110 a 4 in accordance with input profiles similarto those when the loads applied to the left and right hands of the user1 are equal. In this way, the assistance apparatus 100 assists a user inwalking while carrying no object. After step S008, the drive controlunit 122 proceeds to step S006.

In step S009 and the subsequent steps, the drive control unit 122operates in the normal walking mode. In step S009, the drive controlunit 122 acquires a gait phase predicted by the gait timing detectionunit 123. Then, in step S010, the drive control unit 122 controls themotors 114 a 1 to 114 a 4 on the basis of the acquired gait phase togenerate tensions in the wires 110 a 1 to 110 a 4 in accordance withpreset input profiles for assisting the user 1 in walking. The inputprofiles used in step S010 may be the same as the input profiles used instep S008. The drive control unit 122 controls the tensions of the wires110 a 1 to 110 a 4 on the basis of the tensions of the wires 110 a 1 to110 a 4, which are respectively acquired from the force sensors 115 a 1to 115 a 4, to assist flexion and extension of the left and right legsof the user 1. In this way, the assistance apparatus 100 assists a userin walking while carrying no object.

Then, in step S011, the drive control unit 122 determines whether a stopinstruction for stopping assistance provided by the assistance apparatus100 has been acquired from the user 1. If the stop instruction has beenacquired (Yes in step S011), the drive control unit 122 stops theoperation of the assistance apparatus 100 and terminates the series ofprocesses. If no stop instruction is acquired (No in step S011), theprocess returns to step S009. The stop instruction may be an instructionfor changing the operation mode.

As described above, the assistance apparatus 100 assists a user inwalking in accordance with the normal walking mode or the objecttransport walking mode, which is selected by the user. In the objecttransport walking mode, the assistance apparatus 100 changes the balanceof the tensions to be generated in the wires 110 a 1 to 110 a 4 inaccordance with, for example, the loads applied to the left and righthands of a user who is carrying an object, and assists the user inaccordance with the state of the user.

-   3-2. Details of Assistance Operation of Assistance Apparatus

The assistance operation of an assistance apparatus will be described indetail. The following describes an operation of an assistance apparatusfor assisting a user in walking when the user walks forward whilecarrying, or holding, an object such as an item. Specifically, thefollowing describes a relationship between a wire for which a tension isto be increased and the timing of increasing the tension of the wire inassistance for flexion and extension of each of the left and right legsof a user who is walking forward. The operation of the assistanceapparatus 100 according to the embodiment and the operation of theassistance apparatus 200 according to the modification are the same,except that the number of wires in which tensions are to be generatedfor assistance for flexion and extension and maximum tension values aredifferent. Thus, the following describes the operation of the assistanceapparatus 100 according to the embodiment, with no description given ofthe operation of the assistance apparatus 200 according to themodification.

The drive control unit 122 of the assistance apparatus 100 determines,based on a wire-tension relationship for a type of assistance, namely,either of flexion and extension, wires in which tensions are to begenerated, pulling tensions of the wires, and the timing at which andthe period during which the tensions of the wires are generated, andassists motions of the user. For example, FIG. 25 illustrates an exampleoperation of the assistance apparatus 100 for assisting a user inwalking forward while carrying an object. FIG. 25 illustrates a casewhere the loads applied to the left and right hands of the user areequal. Also when assisting a user in walking forward while carrying noobject, the assistance apparatus 100 operates in a way similar to thatin the example illustrated in FIG. 25.

In FIG. 25, a relationship is illustrated among a gait state of a user,a gait phase of each leg, and the swing phase and stance phase of eachleg. In the illustration of FIG. 25, the gait phase of each leg, wiresin which tensions are to be generated, and the states of the tensions ofthe wires, that is, the input profiles of wire tensions, are associatedwith each other. An input profile of a wire tension represents the ratioof a wire tension to a maximum tension to be generated in each wire(also referred to as tension gain). For example, when the tension gainof each wire is 100 N, a tension to be actually generated is representedby an expression of a tension value included in the input profile xtension gain. During a period of 0 to 100% of a gait phase, theassistance apparatus 100 produces a wire tension while changing the wiretension, with a maximum tension being 100 N.

In the example illustrated in FIG. 25, the assistance apparatus 100assists both flexion and extension of the left and right legs of theuser. As described above, the assistance apparatus 100 generates atension in the wire 110 a 1 to apply an assistance force for flexion tothe left leg, and generates a tension in the wire 110 a 2 to apply anassistance force for extension to the left leg. The assistance apparatus100 generates a tension in the wire 110 a 3 to apply an assistance forcefor flexion to the right leg, and generates a tension in the wire 110 a4 to apply an assistance force for extension to the right leg. Theassistance apparatus 100 may assist either flexion or extension of theleft and right legs of the user, instead of both flexion and extensionof the left and right legs of the user.

In FIG. 25, the gait phase of the right leg is used as a reference gaitphase. In the gait phase of the right leg, heel strike of the right legoccurs at 0%, and heel strike of the left leg occurs at 50%. In thisembodiment, as a non-limiting example, a time point of 0% of the gaitphase of the right leg corresponds to a time point of 50% of the gaitphase of the left leg. In the example illustrated in FIG. 25, the gaitphase of the right leg is used as a reference gait phase, forconvenience of illustration. The gait phase of either leg may be used asa reference gait phase, and the gait phase of one leg need not be usedas a reference gait phase.

The stance phase of the right leg is a period of 0% or more and 60% orless of the gait phase of the right leg, and the swing phase of theright leg is a period of more than 60% and less than 100% of the gaitphase of the right leg.

The swing phase of the left leg is a period of more than 60% and lessthan 100% of the gait phase of the left leg, and the stance phase of theleft leg is a period of 100% or more and 160% or less of the gait phaseof the left leg. In the gait phase of the left leg, a period of morethan 60% and less than 100% of the gait phase of the left leg, which isthe swing phase of the left leg, is included in a first gait cycle ofthe left leg, and a period of 100% or more and 160% or less of the gaitphase of the left leg, which is the stance phase of the left leg, isincluded in a second gait cycle of the left leg, which is subsequent tothe first gait cycle of the left leg. That is, a period of 100% or moreand 160% or less of the gait phase of the left leg corresponds to aperiod of 0% or more and 60% or less of the second gait phase of theleft leg. In the following description, a gait phase represented using avalue greater than or equal to 100% means a gait phase subsequent to agait phase represented using a value of 0% to 100%. In FIG. 25,furthermore, a gait phase represented using a value over 100% may beconverted into a value of 0% to 100% and represented using the value of0% to 100%.

When assisting the user in walking forward, for example, the assistanceapparatus 100 applies an assistance force for flexion to the left leg ata timing of about 40% of the gait phase of the left leg. A timing ofabout 40% of the gait phase of the left leg is included in the stancephase of the left leg and the swing phase of the right leg.Specifically, a timing of about 40% of the gait phase of the left leg isa timing immediately before the right leg touches the ground during theswing phase. At this time, the center of gravity of the body of the usershifts forward. When assisting the user in walking forward, for example,the assistance apparatus 100 applies an assistance force for flexion tothe right leg at a timing of about 40% of the gait phase of the rightleg. A timing of about 40% of the gait phase of the right leg isincluded in the swing phase of the left leg and the stance phase of theright leg. Specifically, a timing of about 40% of the gait phase of theright leg is a timing immediately before the left leg touches the groundduring the swing phase. At this time, the center of gravity of the bodyof the user shifts forward.

Further, the assistance apparatus 100 applies an assistance force forextension to the left leg at a timing of about 75% of the gait phase ofthe left leg, for example. A timing of about 75% of the gait phase ofthe left leg is included in the swing phase of the left leg and thestance phase of the right leg. Specifically, a timing of about 75% ofthe gait phase of the left leg is a timing in the middle of moving theleft leg of the user forward during the swing phase and is included inthe period during which the center of gravity of the body of the usershifts from backward to forward. Further, the assistance apparatus 100applies an assistance force for extension to the right leg at a timingof about 75% of the gait phase of the right leg, for example. A timingof about 75% of the gait phase of the right leg is included in thestance phase of the left leg and the swing phase of the right leg.Specifically, a timing of about 75% of the gait phase of the right legis a timing in the middle of moving the right leg of the user forwardduring the swing phase and is included in the period during which thecenter of gravity of the body of the user shifts from backward toforward.

When assisting the user in walking forward, the assistance apparatus 100generates a tension greater than or equal to a first threshold value ineach of the wires 110 a 1 to 110 a 4. In the example illustrated in FIG.25, the respective tensions of the wires 110 a 1 to 110 a 4 are 100 N,for example. The first threshold value may be a tension value thatallows the user to recognize that flexion or extension is promoted by atension generated in a wire. The first threshold value is, for example,40 N, which is 40% of 100 N. In the example illustrated in FIG. 25, theassistance apparatus 100 generates a wire tension in each of the wires110 a 1 to 110 a 4 in such a manner that the wire tension graduallyincreases, reaches a maximum tension, and then gradually decreasesduring the period of generation of the wire tension. The input profilesof the wire tensions generated in the wires 110 a 1 to 110 a 4 by theassistance apparatus 100 each exhibit a waveform that is convex curve.In this example, the maximum tension is 100 N.

To assist flexion of the left leg, for example, the assistance apparatus100 continuously generates a tension in the wire 110 a 1 during theentirety of a first period, which is a period of 40% or more and 85% orless of the gait phase of the left leg. Then, the assistance apparatus100 generates a tension greater than or equal to the first thresholdvalue in the wire 110 a 1 during at least a potion of the first period.In the first period, the left leg shifts from the stance phase to theswing phase. Applying an assistance force for flexion to the left leg inthe shift from the stance phase to the swing phase allows the user toeasily raise the left leg and ensures that the user can easily walk.

In the example illustrated in FIG. 25, the assistance apparatus 100generates no tension in the wire 110 a 1 during a fifth period, which isa period other than the first period. The fifth period may be a periodof 0% or more and less than 40% of the gait phase of the left leg and aperiod of more than 85% and less than 100% of the gait phase of the leftleg. However, the assistance apparatus 100 may generate a tension duringthe fifth period. For example, the assistance apparatus 100 may generatea tension less than a fourth threshold value in the wire 110 a 1 duringthe fifth period. The fourth threshold value is a tension value that issmaller than the first threshold value and that is not perceivable bythe user, for example. For example, the fourth threshold value may be atension value that prevents the wire 110 a 1 from loosening. The fourththreshold value is a value that is 0.2 to 0.4 times the first thresholdvalue or is 10 N, for example. In the specification and the appendedclaims, generation of a tension less than the fourth threshold valuemeans generation of a tension greater than or equal to 0 and less thanthe fourth threshold value and includes generation of a tension of 0.

The start timing of the first period may be included in a period of 35%or more and 55% or less of the gait phase of the left leg. The endtiming of the first period may be included in a period of 80% or moreand 90% or less of the gait phase of the left leg. In the exampleillustrated in FIG. 25, the wire tension is maximum at a timing of 65%of the gait phase of the left leg. However, the wire tension may bemaximum at a time during a period of 60% or more and 70% or less of thegait phase of the left leg. Thus, the first period may be a period of35% or more and 90% or less of the gait phase of the left leg.

To assist extension of the left leg, for example, the assistanceapparatus 100 continuously generates a tension in the wire 110 a 2during the entirety of a second period, which is a period of 75% or moreand 120% or less of the gait phase of the left leg. Then, the assistanceapparatus 100 generates a tension greater than or equal to the firstthreshold value in the wire 110 a 2 during at least a portion of thesecond period. In the second period, the left leg shifts from the swingphase to the stance phase. Applying an assistance force for extension tothe left leg in the shift from the swing phase to the stance phaseallows the left leg of the user to touch the ground stably and ensuresthat the user can easily walk. In the example illustrated in FIG. 25,the assistance apparatus 100 generates no tension in the wire 110 a 2during a sixth period, which is a period other than the second period.The sixth period may be a period of more than 20% and less than 75% ofthe gait phase of the left leg. However, the assistance apparatus 100may generate a tension less than the fourth threshold value during thesixth period.

The start timing of the second period may be included in a period of 65%or more and 90% or less of the gait phase of the left leg. The endtiming of the second period may be included in a period of 110% or moreand 125% or less of the gait phase of the left leg. In the exampleillustrated in FIG. 25, the wire tension is maximum at a timing of 100%of the gait phase of the left leg. However, the wire tension may bemaximum at a time during a period of 85% or more and 100% or less of thegait phase of the left leg. Thus, the second period may be a period of65% or more and 125% or less of the gait phase of the left leg, that is,may include a period of 0% or more and 25% or less of the gait phase ofthe left leg and a period of 65% or more and less than 100% of the gaitphase of the left leg.

To assist flexion of the right leg, for example, the assistanceapparatus 100 continuously generates a tension in the wire 110 a 3during the entirety of a third period, which is a period of 40% or moreand 85% or less of the gait phase of the right leg. Then, the assistanceapparatus 100 generates a tension greater than or equal to the firstthreshold value in the wire 110 a 3 during at least a portion of thethird period. In the third period, the right leg shifts from the stancephase to the swing phase. In the example illustrated in FIG. 25, theassistance apparatus 100 generates no tension in the wire 110 a 3 duringa seventh period, which is a period other than the third period.However, the assistance apparatus 100 may generate a tension less thanthe fourth threshold value during the seventh period. The seventh periodmay be a period of 0% or more and less than 40% of the gait phase of theright leg and a period of more than 85% and less than 100% of the gaitphase of the right leg.

The start timing of the third period may be included in a period of 35%or more and 55% or less of the gait phase of the right leg. The endtiming of the third period may be included in a period of 80% or moreand 90% or less of the gait phase of the right leg. In the exampleillustrated in FIG. 25, the wire tension is maximum at a timing of 65%of the gait phase of the right leg. However, the wire tension may bemaximum at a time during a period of 60% or more and 70% or less of thegait phase of the right leg. Thus, the third period may be a period of35% or more and 90% or less of the gait phase of the right leg.

To assist extension of the right leg, for example, the assistanceapparatus 100 continuously generates a tension in the wire 110 a 4during the entirety of a fourth period, which is a period of 75% or moreand 120% or less of the gait phase of the right leg. Then, theassistance apparatus 100 generates a tension greater than or equal tothe first threshold value in the wire 110 a 4 during at least a portionof the fourth period. In the fourth period, the right leg shifts fromthe swing phase to the stance phase. In the example illustrated in FIG.25, the assistance apparatus 100 generates no tension in the wire 110 a4 during an eighth period, which is a period other than the fourthperiod. The eighth period may be a period of more than 20% and less than75% of the gait phase of the right leg. However, the assistanceapparatus 100 may generate a tension less than the fourth thresholdvalue during the eighth period.

The start timing of the fourth period may be included in a period of 65%or more and 90% or less of the gait phase of the right leg. The endtiming of the fourth period may be included in a period of 110% or moreand 125% or less of the gait phase of the right leg. In the exampleillustrated in FIG. 25, the wire tension is maximum at a timing of 100%of the gait phase of the right leg. However, the wire tension may bemaximum at a time during a period of 85% or more and 100% or less of thegait phase of the right leg. Thus, the fourth period may be a period of65% or more and 125% or less of the gait phase of the right leg, thatis, may include a period of 0% or more and 25% or less of the gait phaseof the right leg and a period of 65% or more and less than 100% of thegait phase of the right leg.

As described above, during the entirety of a period corresponding toeach input profile of a wire tension, the assistance apparatus 100continuously generates a tension in the wire corresponding to the inputprofile. However, the embodiment is not limited to this. The assistanceapparatus 100 may temporarily stop the generation of the tension in thewire during the period corresponding to the input profile. In this case,a load imposed on the leg of the user by the assistance apparatus 100 isreduced, and the load felt by the user on which the assistance apparatus100 acts is reduced.

The input profiles of wire tensions illustrated in FIG. 25 are set sothat the tension of each wire rises earlier than a desired time point byseveral percent (%) of the gait phase in consideration of a time delayfrom when the drive control unit 122 outputs a signal to thecorresponding motor to when a tension is actually generated in the wire.For example, in the example illustrated in FIG. 25, input profiles ofwire tensions are created so that the tension of each wire rises earlierthan a desired time point by approximately 5%. For assistance forflexion, the assistance apparatus 100 provides assistance so that theassistance for flexion is completed immediately before the heel strikesthe ground. Thus, input profiles of wire tensions are created so thatassistance for flexion ends at a time during a period of 80% or more and90% or less of the gait phase of the each leg in order to completeassistance for flexion at a timing of about 100% of the gait phase ofeach leg in consideration of a delay of output of the tension of eachwire.

As described above, in the example illustrated in FIG. 25, a case isillustrated in which the loads applied to the left and right hands ofthe user are equal. However, when the loads applied to the left andright hands of the user are different, the assistance apparatus 100controls the tensions of the wires 110 by using input profiles differentfrom the input profiles of the wire tensions illustrated in FIG. 25.

Specifically, the assistance apparatus 100 detects loads applied to theleft and right hands of a user who is carrying an object, on the basisof sensor values acquired from the contact sensors 301 a and 301 b.Further, the assistance apparatus 100 changes the input profiles of thewire tensions illustrated in FIG. 25 on the basis of a differencebetween the loads applied to the left and right hands, and controls thetensions of the wires 110 a 1 to 110 a 4 by using the changed inputprofiles to assist the user in walking.

For example, as illustrated in FIG. 26A to FIG. 26C, the loads appliedto the left and right hands of the user vary depending on how the usercarries an object. FIG. 26A to FIG. 26C are diagrams illustratingexamples of how a user carries an object.

In the example illustrated in FIG. 26A, the user 1 wearing theassistance apparatus 100 carries an object A in such a manner that theobject A is held in the left and right hands at an equal heightpositions. That is, the user 1 carries the object A with the left andright arms kept in balanced postures. In this case, the loads applied tothe left and right hands of the user 1 are equal. Thus, the drivecontrol unit 122 controls the tensions of the wires 110 a 1 to 110 a 4by using the input profiles of the wire tensions illustrated in FIG. 25.

In the input profiles illustrated in FIG. 25, the input profile of thetension of the wire 110 a 1 during the first period in the gait phase ofthe left leg and the input profile of the tension of the wire 110 a 3during the third period in the gait phase of the right leg are similar.That is, the maximum tension of the wire 110 a 1 in the first period andthe maximum tension of the wire 110 a 3 in the third period are equal.

Further, the input profile of the tension of the wire 110 a 2 during thesecond period in the gait phase of the left leg and the input profile ofthe tension of the wire 110 a 4 during the fourth period in the gaitphase of the right leg are similar. That is, the maximum tension of thewire 110 a 2 in the second period and the maximum tension of the wire110 a 4 in the fourth period are equal.

In the example illustrated in FIG. 26B, the user 1 wearing theassistance apparatus 100 carries an object A in such a manner that theobject A is held in the left and right hands at unequal heightpositions. Specifically, the height position of the right hand is higherthan the height position of the left hand. In this case, the loadapplied to the left hand of the user 1 is larger than the load appliedto the right hand of the user 1. Accordingly, the center of gravity ofthe body of the user 1 shifts leftward from the center, resulting in anincrease in the load on the left leg of the user 1. Thus, the drivecontrol unit 122 uses input profiles of the wire tensions obtained bychanging the input profiles of the wire tensions illustrated in FIG. 25in such a manner that the tensions of the wires 110 a 1 and 110 a 2 ofthe left leg are greater than the tensions of the wires 110 a 3 and 110a 4 of the right leg. In this embodiment, the relationship between thetension of the wires 110 a 1 and 110 a 2 of the left leg and the tensionof the wires 110 a 3 and 110 a 4 of the right leg is defined on thebasis of the tension ratio, as a non-limiting example. Alternatively,for example, the relationship may be defined on the basis of the tensiondifference.

Specifically, in the case described above, the ratio of the tension ofthe wires 110 a 1 and 110 a 2 of the left leg to the tension of thewires 110 a 3 and 110 a 4 of the right leg is represented as a firstratio. That is, first ratio=(tension of wire of left leg)/(tension ofwire of right leg) holds. The first ratio is set to any value in therange of 1.2 or more and 2.0 or less. The first ratio increases as thedifference between the load applied to the left hand and the loadapplied to the right hand increases. However, the first ratio may be afixed value. When the first ratio is a fixed value, the first ratio maybe determined in advance and stored in the storage unit 125, or may bedetermined by the user 1 through the input device 140 or the terminaldevice 150 and stored in the storage unit 125. For example, in the inputdevice 140 illustrated in FIG. 8, the “left-handed” button 145 and the“right-handed” button 146 may have a function of decreasing andincreasing the first ratio.

The first ratio includes the tensions of a pair of wires of the left andright legs, which are used to assist the same motion. Examples of thetensions of a pair of wires making up the first ratio include a pair ofthe maximum tension of the wire 110 a 1 in the first period during thegait phase of the left leg and the maximum tension of the wire 110 a 3in the third period during the gait phase of the right leg, and a pairof the maximum tension of the wire 110 a 2 in the second period duringthe gait phase of the left leg and the maximum tension of the wire 110 a4 in the fourth period during the gait phase of the right leg.

In the example illustrated in FIG. 26B, the first ratio is set to, forexample, “1.2”. In this case, the drive control unit 122 controls thetensions of the wires 110 in accordance with input profiles of wiretensions illustrated in FIG. 27. FIG. 27 is a diagram illustrating anexample operation of the assistance apparatus 100 for assisting a userin walking forward while carrying an object in such a manner that theload applied to the left hand is larger than the load applied to theright hand. In the example illustrated in FIG. 27, the maximum tensionsto be generated in the wires 110 a 1 and 110 a 2 of the left leg are 100N, and the maximum tensions to be generated in the wires 110 a 3 and 110a 4 of the right leg are 83 N. The waveforms of the input profiles ofthe tensions of the wires 110 a 3 and 110 a 4 are entirely changed inaccordance with the reduced maximum tensions. In the example illustratedin FIG. 27, the tension generation timings, the tension generationperiods, and the timings at which the tensions are maximum in thewaveforms of the input profiles of the tensions of the wires 110 a 3 and110 a 4 remain unchanged from those illustrated in FIG. 25.

In the example illustrated in FIG. 27, the tension of the wire 110 a 1in the first period, which is represented by f1(θ), the tension of thewire 110 a 2 in the second period, which is represented by f2(θ), thetension of the wire 110 a 3 in the third period, which is represented byf3(θ), and the tension of the wire 110 a 4 in the fourth period, whichis represented by f4(θ), where θ denotes a gait phase, may be defined asfollows: f1(θ)/f3(θ)=first ratio, f2(θ)/f4(θ)=first ratio, and firstratio=1.2. Note that the gait phase θ may not include a gait phase inwhich tension application is started. Note that the gait phase θ may notinclude a gait phase in which tension application is finished.

Accordingly, the drive control unit 122 makes the tension of the wire110 a 1 in the first period during the gait phase of the left leg andthe tension of the wire 110 a 2 in the second period during the gaitphase of the left leg greater than the tension of the wire 110 a 3 inthe third period during the gait phase of the right leg and the tensionof the wire 110 a 4 in the fourth period during the gait phase of theright leg.

As illustrated in FIG. 27, making the maximum tensions of the wires 110a 1 and 110 a 2 of the left leg greater than the maximum tensions of thewires 110 a 3 and 110 a 4 of the right leg is most effective to assist auser in walking. The user receives a larger assistance force at the leftleg, which bears a larger load, and a smaller assistance force at theright leg, which bears a smaller load, and can thus smoothly walk whilefeeling uniform loads being imposed on the left and right legs. Further,there is a tendency that the center of gravity of the body of a user whocarries an object is moved forward. Accordingly, increasing the tensionsto be generated in the wires 110 a 2 and 110 a 4 in the back part of thebody of the user to increase an assistance force for extension iseffective to keep the center of gravity of the body of the user in theupright state. Thus, only the maximum tension of the wire 110 a 2 of theleft leg may be made larger than the maximum tensions of the wires 110 a3 and 110 a 4 of the right leg, and the maximum tension of the wire 110a 1 of the left leg may be made equal to the maximum tensions of thewires 110 a 3 and 110 a 4 of the right leg. Also in this case, a userwho carries an object can feel relatively uniform loads being imposed onthe left and right legs.

When the load applied to the right hand of the user 1 is larger than theload applied to the left hand of the user 1, the first ratio is given by(tension of wire of right leg)/(tension of wire of left leg). Theassistance apparatus 100 provides assistance based on the first ratio insuch a manner that the tensions to be generated in the wires 110 a 3 and110 a 4 of the right leg are greater than the tensions to be generatedin the wires 110 a 1 and 110 a 2 of the left leg.

Accordingly, the drive control unit 122 makes the tension of the wire110 a 3 in the third period during the gait phase of the right leg andthe tension of the wire 110 a 4 in the fourth period during the gaitphase of the right leg greater than the tension of the wire 110 a 1 inthe first period during the gait phase of the left leg and the tensionof the wire 110 a 2 in the second period during the gait phase of theleft leg.

In the example illustrated in FIG. 26C, the user 1 wearing theassistance apparatus 100 carries an object A only using the left hand.In this case, the load applied to the left hand of the user 1 is muchlarger than the load applied to the right hand of the user 1, and thecenter of gravity of the body of the user 1 shifts leftward from thecenter, resulting in an increase in the load on the left leg of the user1. Thus, the drive control unit 122 controls the tensions of the wires110 a 1 to 110 a 4 by using input profiles of wire tensionscorresponding to a first ratio larger than that in the exampleillustrated in FIG. 26B. Such a first ratio is set to any value in therange of 1.2 or more and 3.0 or less. In the example illustrated in FIG.26C, the first ratio is set to, for example, “1.5”. In this case, thedrive control unit 122 controls the tensions of the wires 110 a 1 to 110a 4 in accordance with input profiles of wire tensions illustrated inFIG. 28. FIG. 28 is a diagram illustrating another example operation ofthe assistance apparatus 100 for assisting a user in walking forwardwhile carrying an object in such a manner that the load applied to theleft hand is larger than the load applied to the right hand. In theexample illustrated in FIG. 28, the maximum tensions to be generated inthe wires 110 a 1 and 110 a 2 of the left leg are 100 N, and the maximumtensions to be generated in the wires 110 a 3 and 110 a 4 of the rightleg are 67 N. The waveforms of the input profiles of the tensions of thewires 110 a 3 and 110 a 4 are entirely changed in accordance with thereduced maximum tensions.

In the example illustrated in FIG. 28, the tension of the wire 110 a 1in the first period, which is represented by g1(θ), the tension of thewire 110 a 2 in the second period, which is represented by g2(θ), thetension of the wire 110 a 3 in the third period, which is represented byg3(θ), and the tension of the wire 110 a 4 in the fourth period, whichis represented by g4(θ), where θ denotes a gait phase, may be defined asfollows: g1(θ)/g3(θ)=first ratio, g2(θ)/g4(θ)=first ratio, and firstratio=1.5. Note that the gait phase θ may not include a gait phase inwhich tension application is started. Note that the gait phase θ may notinclude a gait phase in which tension application is finished.

As described above, the assistance apparatus 100 determines the firstratio on the basis of the difference between the loads applied to theleft and right hands of a user. Specifically, as the differenceincreases, the first ratio increases. Further, the assistance apparatus100 changes the input profiles of wire tensions illustrated in FIG. 25,in which the first ratio is equal to 1, by making the wire tensions ofthe left and right legs different from each other in accordance with thefirst ratio, and controls the tensions of the wires 110 a 1 to 110 a 4in accordance with the changed input profiles. That is, the assistanceapparatus 100 changes the balance between the wire tension of the leftleg and the wire tension of the right leg on the basis of the differencebetween the loads applied to the left and right hands of the user. Thedifference between the loads applied to the left and right hands may berepresented as the discrepancy between the loads applied to the left andright hands, the ratio of the loads applied to the left and right hands,or the like. The changed input profiles may be stored in the storageunit 125 in advance or may be calculated by the drive control unit 122.Further, as described with reference to FIG. 24, even if the manner inwhich a user carries an object is changed between, for example, theexamples illustrated in FIG. 26A to FIG. 26C during walking, theassistance apparatus 100 can change the balance between the wiretensions of the left and right legs in accordance with the changedmanner.

-   3-3-1. First Modification of Assistance Operation of Assistance    Apparatus

A first modification of the assistance operation of the assistanceapparatus 100 will be described. In this modification, the assistanceapparatus 100 makes the wire tension to be generated in the wires 110 a1 and 110 a 2 of the left leg different from the wire tension to begenerated in the wires 110 a 3 and 110 a 4 of the right leg on the basisof information on the dominant hand of a user. The information on thedominant hand of a user is information indicating which of the left andright hands is the dominant hand of the user. The drive control unit 122of the assistance apparatus 100 may acquire information on the dominanthand of the user, which is stored in the storage unit 125 in advance, ormay acquire information on the dominant hand of the user, which is inputvia the input device 140 or the terminal device 150.

As illustrated in FIG. 8, when the input device 140 is used, the userpresses the “left-handed” button 145 or the “right-handed” button 146 todetermine the dominant hand. The drive control unit 122 receives asignal generated by the “left-handed” button 145 or the “right-handed”button 146 to acquire information indicating which of the left and righthands is the dominant hand. It may be possible to set a musculardifference between the dominant hand and the non-dominant hand. Forexample, in the input device 140, a muscular difference may be set inaccordance with the number of times the “left-handed” button 145 or the“right-handed” button 146 is pressed. Specifically, for example, as thenumber of times the “left-handed” button 145 is pressed increases, themuscle strength of the left hand may be set to be higher than that ofthe right hand. The same applies to the “right-handed” button 146. Themethod for setting a muscular difference is not limited to thatdescribed above, and any method may be used. For example, a button, adial, a slide button, a lever, or any other suitable device for settinga muscular difference may be disposed. The timing at which informationon the dominant hand of a user is input may be, for example, any timingin a process during which the user performs an operation of determiningthat an operation mode is to be implemented.

A user is more likely to place a larger load on the dominant hand whencarrying an object in both hands. Further, a user is more likely tocarry an object in the dominant hand when carrying the object in onehand. Thus, the center of gravity of the body of a user who carries anobject shifts toward the dominant hand, and the load on the leg on thesame side as the dominant hand is larger. For example, when the dominanthand is the left hand, the load on the left leg is larger than that onthe right leg. When the dominant hand is the right hand, the load on theright leg is larger than that on the left leg. Thus, the drive controlunit 122 changes the input profiles of the wire tensions illustrated inFIG. 25 in such a manner that the tension of the wires 110 of the leg onthe same side as the dominant hand is greater than the tension of thewires 110 of the leg on the side opposite to the dominant hand, and usesthe changed input profiles. For example, when the left hand is thedominant hand, in the changed input profiles, the tensions to begenerated in the wires 110 a 1 and 110 a 2 of the left leg are greaterthan the tensions to be generated in the wires 110 a 3 and 110 a 4 ofthe right leg.

Also in this modification, the relationship between the tension of thewires 110 a 1 and 110 a 2 of the left leg and the tension of the wires110 a 3 and 110 a 4 of the right leg is defined on the basis of thetension ratio, as a non-limiting example. Alternatively, for example,the relationship may be defined on the basis of the tension difference.Specifically, a second ratio similar to the first ratio is used. Whenthe dominant hand is the left hand, second ratio=(tension of wire ofleft leg)/(tension of wire of right leg) holds. The second ratio is setto any value in the range of 1.2 or more and 1.5 or less. The drivecontrol unit 122 may use the second ratio, which is determined inadvance, or may determine a second ratio on the basis of the musculardifference described above between the dominant hand and thenon-dominant hand. In this case, as the muscular difference increases,the second ratio increases. For example, when the dominant hand is theleft hand and the second ratio is “1.2”, as in the case where there is adifference between the loads applied to the left and right hands, thedrive control unit 122 controls the tensions of the wires 110 inaccordance with the input profiles of the wire tensions illustrated inFIG. 27.

When the dominant hand is the left hand, the drive control unit 122makes the tension of the wire 110 a 1 in the first period during thegait phase of the left leg and the tension of the wire 110 a 2 in thesecond period during the gait phase of the left leg greater than thetension of the wire 110 a 3 in the third period during the gait phase ofthe right leg and the tension of the wire 110 a 4 in the fourth periodduring the gait phase of the right leg. When the dominant hand is theright hand, the drive control unit 122 makes the tension of the wire 110a 3 in the third period during the gait phase of the right leg and thetension of the wire 110 a 4 in the fourth period during the gait phaseof the right leg greater than the tension of the wire 110 a 1 in thefirst period during the gait phase of the left leg and the tension ofthe wire 110 a 2 in the second period during the gait phase of the leftleg.

Also in this modification, for example, when the dominant hand is theleft hand, both the maximum tensions of the wires 110 a 1 and 110 a 2 ofthe left leg may be made larger than the maximum tensions of the wires110 a 3 and 110 a 4 of the right leg, or only the maximum tension of thewire 110 a 2 of the left leg may be made larger than the maximumtensions of the wires 110 a 3 and 110 a 4 of the right leg.

As described above, the assistance apparatus 100 determines the secondratio on the basis of information on the dominant hand of a user.Further, the assistance apparatus 100 changes the input profiles of wiretensions illustrated in FIG. 25, in which the second ratio is equal to1, by making the wire tensions of the left and right legs different fromeach other in accordance with the second ratio, and controls thetensions of the wires 110 in accordance with the changed input profiles.That is, the assistance apparatus 100 changes the balance between thewire tension of the left leg and the wire tension of the right leg onthe basis of information on the dominant hand of the user. The changedinput profiles may be stored in the storage unit 125 in advance or maybe calculated by the drive control unit 122.

As in this modification, when changing the balance between the wiretensions of the left and right legs on the basis of information on thedominant hand of a user, the assistance apparatus 100 may or may notapply a change in the balance between the wire tensions of the left andright legs based on the difference between the loads applied to the leftand right hands of the user. When the change in the balance is notapplied, detection performed by the contact sensors 301 a and 301 b isno longer necessary. Thus, the assistance apparatus 100 can besimplified, and the process for controlling wire tensions can besimplified. When the change in the balance is applied, elaborate wiretension control that reflects the state of a user who carries an objectand the characteristics of the user is feasible.

-   3-3-2. Second Modification of Assistance Operation of Assistance    Apparatus

A second modification of the assistance operation of the assistanceapparatus 100 will be described. In this modification, the assistanceapparatus 100 detects that a user is carrying an object in one hand onthe basis of the loads applied to the left and right hands. When a usercarries an object in one hand, in the embodiment, the assistanceapparatus 100 makes the tensions of the wires 110 of the leg on the sameside as the hand carrying the object greater than the tensions of thewires 110 of the leg on the opposite side. In this modification, incontrast, the assistance apparatus 100 makes the tensions of a differentcombination of wires 110 from that in the embodiment greater than thetensions of the other wires 110.

First, among the operations of the assistance apparatus 100 according tothis modification, an operation of detecting that a user is carrying anobject in one hand on the basis of the loads applied to the left andright hands will be described. Referring to FIG. 3, FIG. 10A, and FIG.10B, the grasp recognition unit 121 detects loads applied to the leftcontact sensor 301 a and the right contact sensor 301 b on the basis ofsensor values acquired from the left contact sensor 301 a and the rightcontact sensor 301 b, and detects loads applied to the left and righthands of the user 1 accordingly.

A condition in which the load, or force, applied to the left contactsensor 301 a is greater than or equal to a second threshold value and inwhich no load is applied to the right contact sensor 301 b isrepresented as a first condition. A condition in which the load appliedto the right contact sensor 301 b is greater than or equal to the secondthreshold value and in which no load is applied to the left contactsensor 301 a is represented as a second condition. When the firstcondition is satisfied, the drive control unit 122 detects that the user1 is carrying an object only in the left hand. When the second conditionis satisfied, the drive control unit 122 detects that the user 1 iscarrying an object only in the right hand.

The second threshold value may be a value that allows a user to feel,when a load greater than or equal to the second threshold value isexerted on one hand, an increase in the load on the leg on the same sideas the hand. The second threshold value may have a temporal meaning. Forexample, keeping a value greater than or equal to the second thresholdvalue over a predetermined time period or longer may represent being avalue greater than or equal to the second threshold value. The secondthreshold value may be set for each user. The second threshold value maybe selected from within a range of voltage values 50 to 220, which isnormalized with, for example, 0 to 255, and is, for example, 200.Further, the expression “no load being applied to the left contactsensor 301 a and the right contact sensor 301 b” is used to include notonly a load of “0” but also a load smaller than a third threshold value.If a load greater than or equal to 0 and less than the third thresholdvalue is applied to the left contact sensor 301 a and the right contactsensor 301 b, the drive control unit 122 regards no load as beingapplied to the left contact sensor 301 a and the right contact sensor301 b. The third threshold value may be a value such as a voltage valuenormalized with 0 to 255. The third threshold value may be selected fromwithin a range of 10 to 50, and is, for example, 20.

As described above, the drive control unit 122 detects whether the user1 is carrying an object only in the left hand or the right hand, inaccordance with whether the first condition or the second condition issatisfied. If the load applied to one of the left contact sensor 301 aand the right contact sensor 301 b is greater than or equal to thesecond threshold value and the load applied to the other contact sensoris greater than or equal to the third threshold value, the drive controlunit 122 may detect that the user 1 is carrying an object in both hands.

Then, the operations of the assistance apparatus 100 when the firstcondition is satisfied and when the second condition is satisfied willbe described. First, when the first condition is satisfied, the user 1carries an object only in the left hand and the load imposed on the leftleg is larger than that on the right leg. Thus, the drive control unit122 uses input profiles of wire tensions obtained by changing the inputprofiles of the wire tensions illustrated in FIG. 25 in such a mannerthat the tensions of the wire 110 a 2 of the left leg and the wire 110 a3 of the right leg are greater than the tensions of the wire 110 a 1 ofthe left leg and the wire 110 a 4 of the right leg. That is, theassistance apparatus 100 changes the balance of the tensions of thewires 110 a 1 to 110 a 4. Specifically, the maximum tension of the wire110 a 2 in the second period during the gait phase of the left leg ismade greater than the maximum tension of the wire 110 a 4 in the fourthperiod during the gait phase of the right leg. Further, the maximumtension of the wire 110 a 3 in the third period during the gait phase ofthe right leg is made greater than the maximum tension of the wire 110 a1 in the first period during the gait phase of the left leg.

Accordingly, the drive control unit 122 makes the tension of the wire110 a 2 in the second period during the gait phase of the left leggreater than the tension of the wire 110 a 4 in the fourth period duringthe gait phase of the right leg, and makes the tension of the wire 110 a3 in the third period during the gait phase of the right leg greaterthan the tension of the wire 110 a 1 in the first period during the gaitphase of the left leg. Thus, the assistance apparatus 100 makes theassistance force for extension of the left leg and the assistance forcefor flexion of the right leg greater than the assistance force forextension of the right leg and the assistance force for flexion of theleft leg, respectively.

Further, the relationship between the wire tensions after the balance ischanged is defined on the basis of a third ratio similar to the firstratio used in the embodiment, as a non-limiting example. Alternatively,for example, the relationship may be defined on the basis of the tensiondifference. In the case of the third ratio, third ratio =(tension ofwire 110 a 2)/(tension of wire 110 a 4), and third ratio=(tension ofwire 110 a 3)/(tension of wire 110 a 1) hold. The third ratio is set toany value in the range of 1.2 or more and 2.0 or less. The third ratioincreases as the difference between the load applied to the left handand the load applied to the right hand increases. However, the thirdratio may be a fixed value. When the third ratio is a fixed value, thethird ratio may be determined in advance and stored in the storage unit125, or may be determined by the user 1 through the input device 140 orthe terminal device 150 and stored in the storage unit 125. For example,in the input device 140 illustrated in FIG. 8, the “left-handed” button145 and the “right-handed” button 146 may have a function of decreasingand increasing the third ratio.

When the first condition is satisfied, the drive control unit 122controls the tensions of the wires 110 in accordance with input profilesof wire tensions illustrated in FIG. 29, which are obtained by changingthe input profiles of the wire tensions illustrated in FIG. 25. FIG. 29is a diagram illustrating an example operation of the assistanceapparatus 100 for assisting a user in walking forward while carrying anobject only in the left hand. In the example illustrated in FIG. 29, thethird ratio is “1.5”, the maximum tensions to be generated in the wire110 a 2 and the wire 110 a 3 are 100 N, and the maximum tensions to begenerated in the wire 110 a 4 and the wire 110 a 1 are 67 N. Thewaveforms of the input profiles of the tensions of the wires 110 a 1 and110 a 4 are entirely changed in accordance with the reduced maximumtensions. In the example illustrated in FIG. 29, the tension generationtimings, the tension generation periods, and the timings at which thetensions are maximum in the waveforms of the input profiles of thetensions of the wires 110 a 1 and 110 a 4 remain unchanged from thoseillustrated in FIG. 25.

In the example illustrated in FIG. 29, the tension of the wire 110 a 1in the first period, which is represented by h1(θ), the tension of thewire 110 a 2 in the second period, which is represented by h2(θ), thetension of the wire 110 a 3 in the third period, which is represented byh3(θ), and the tension of the wire 110 a 4 in the fourth period, whichis represented by h4(θ), where θ denotes a gait phase, may be defined asfollows: h2(θ)/h4(θ)=third ratio, and h3(θ)/h1(θ)=third ratio. Note thatthe gait phase θ may not include a gait phase in which tensionapplication is started. Note that the gait phase θ may not include agait phase in which tension application is finished.

Then, when the second condition is satisfied, the user carries an objectonly in the right hand and the load imposed on the right leg is largerthan that on the left leg. Thus, the drive control unit 122 uses inputprofiles of wire tensions obtained by changing the input profiles of thewire tensions illustrated in FIG. 25 in such a manner that the tensionsof the wire 110 a 4 of the right leg and the wire 110 a 1 of the leftleg are greater than the tensions of the wire 110 a 2 of the left legand the wire 110 a 3 of the right leg. Specifically, the maximum tensionof the wire 110 a 4 in the fourth period during the gait phase of theright leg is made greater than the maximum tension of the wire 110 a 2in the second period during the gait phase of the left leg. Further, themaximum tension of the wire 110 a 1 in the first period during the gaitphase of the left leg is made greater than the maximum tension of thewire 110 a 3 in the third period during the gait phase of the right leg.

Accordingly, the drive control unit 122 makes the tension of the wire110 a 4 in the fourth period during the gait phase of the right leggreater than the tension of the wire 110 a 2 in the second period duringthe gait phase of the left leg, and makes the tension of the wire 110 a1 in the first period during the gait phase of the left leg greater thanthe tension of the wire 110 a 3 in the third period during the gaitphase of the right leg. Thus, the assistance apparatus 100 makes theassistance force for extension of the right leg and the assistance forcefor flexion of the left leg greater than the assistance force forextension of the left leg and the assistance force for flexion of theright leg, respectively. Accordingly, the assistance apparatus 100provides assistance, which is similar to that for the left and rightlegs when the first condition is satisfied, to the right and left legs.

For the third ratio, third ratio=(tension of wire 110 a 4)/(tension ofwire 110 a 2), and third ratio=(tension of wire 110 a 1)/(tension ofwire 110 a 3) hold.

When the second condition is satisfied, the drive control unit 122controls the tension of the wires 110 a 1 to 110 a 4 in accordance withinput profiles of wire tensions illustrated in FIG. 30, which areobtained by changing the input profiles of the wire tensions illustratedin FIG. 25. FIG. 30 is a diagram illustrating an example operation ofthe assistance apparatus 100 for assisting a user in walking forwardwhile carrying an object only in the right hand. In the exampleillustrated in FIG. 30, the third ratio is “1.5”, the maximum tensionsto be generated in the wire 110 a 4 and the wire 110 a 1 are 100 N, andthe maximum tensions to be generated in the wire 110 a 2 and the wire110 a 3 are 67 N. The input profiles of the tensions of the wires 110 a2 and 110 a 3 are configured using a method similar to that for thewires 110 a 1 and 110 a 4 illustrated in FIG. 29.

In the example illustrated in FIG. 30, the tension of the wire 110 a 1in the first period, which is represented by i1(θ), the tension of thewire 110 a 2 in the second period, which is represented by i2(θ), thetension of the wire 110 a 3 in the third period, which is represented byi3(θ), and the tension of the wire 110 a 4 in the fourth period, whichis represented by i4(θ), where θ denotes a gait phase, may be defined asfollows: i4(θ)/i2(θ)=third ratio, and i1(θ)/i3(θ)=third ratio. Note thatthe gait phase θ may not include a gait phase in which tensionapplication is started. Note that the gait phase θ may not include agait phase in which tension application is finished.

The input profiles of the wire tensions illustrated in FIG. 29 and FIG.30 may be created in advance and stored in the storage unit 125, or maybe configured by the drive control unit 122.

The assistance apparatus 100, described above, applies a largerassistance force for extension to the left leg, which bears a largergravitationally downward load due to an object being carried in the lefthand, than that for the right leg, which bears a smaller load, andapplies a larger assistance force for extension to the right leg, whichbears a larger gravitationally downward load due to an object beingcarried in the right hand, than that for the left leg, which bears asmaller load. The assistance force for extension supports a leg bearinga gravitationally downward load and reduces the burden on the leg.Accordingly, the assistance apparatus 100 assists a user in walking witha burden and fatigue of the left and right legs being made uniform andreduced. This enables the user to walk by moving the left and right legsin a well-balanced manner while feeling uniform loads being imposed onthe left and right legs. Further, the assistance apparatus 100 applies alarger assistance force for flexion to the right leg, which bears asmaller load, than that for the left leg, which bears a larger load, andapplies a larger assistance force for flexion to the left leg, whichbears a smaller load, than that for the right leg, which bears a largerload. Thus, the assistance apparatus 100 facilitates and induces theprogress of the user's walking. Further, the assistance apparatus 100applies a larger assistance force to both the left and right legs,rather than to either leg, to provide well-balanced assistance to theleft and right legs.

When a user walking while carrying an object in the left or right handstops walking, the assistance apparatus 100 may change assistanceprovided to the user. In this case, the drive control unit 122 detectsthat the user has stopped walking by using a sensor value of thepressure-sensitive sensor 302 or the inertial measurement unit 303, andfurther identifies a leg bearing a larger load. Then, the drive controlunit 122 changes tension control for the wires 110 a 1 to 110 a 4 on thebasis of the identified result.

When the pressure-sensitive sensor 302 is used, the drive control unit122 acquires the sensor value of the pressure-sensitive sensor 302 onthe left foot and the sensor value of the pressure-sensitive sensor 302on the right foot. A voltage value, which is a sensor value of thepressure-sensitive sensor 302, corresponds to a pressure sensor valueand represents a foot-to-ground contact load. For example, a smallervoltage value of the pressure-sensitive sensor 302 represents a largerfoot-to-ground contact load. The drive control unit 122 detects aleft-foot-to-ground contact load and a right-foot-to-ground contact loadfrom the voltage value of the pressure-sensitive sensor 302 on the leftfoot and the voltage value of the pressure-sensitive sensor 302 on theright foot, respectively, and detects the respective degrees of load onthe left and right legs. Further, when voltage values indicating theground contact of the left foot and the right foot are simultaneouslyacquired from the pressure-sensitive sensors 302 on the left and rightfeet, the drive control unit 122 determines that the user has stoppedwalking.

When the inertial measurement unit 303 is used, the drive control unit122 acquires a sensor value from the acceleration sensor of the inertialmeasurement unit 303. The sensor value of the acceleration sensorcorresponds to acceleration. The drive control unit 122 detects theacceleration of the user in the left-right direction from the sensorvalue of the acceleration sensor, and can thus detect the direction inwhich the center of gravity of the body of the user shifts from theneutral position. Further, the drive control unit 122 acquires a sensorvalue from the gyro sensor of the inertial measurement unit 303. Sincethe inertial measurement unit 303 is placed on the upper half of thebody of the user, the sensor value of the inertial measurement unit 303corresponds to the angular velocity of the upper half of the body. Thedrive control unit 122 can detect the amount by which the upper half ofthe body of the user is inclined forward, backward, or sideways and theamount by which the upper half of the body of the user is rotatedsideways from the sensor value of the gyro sensor. Then, the drivecontrol unit 122 identifies a leg bearing a larger load from thedirection in which the center of gravity of the body shifts in theleft-right direction, the amount by which the upper half of the body isinclined forward, backward, or sideways, and the amount by which theupper half of the body is rotated sideways. When the sensor value of theacceleration sensor indicates that the acceleration in theanterior-posterior direction is 0, the drive control unit 122 determinesthat the user has stopped walking.

After identifying a leg bearing a larger load, the drive control unit122 continuously generates a tension in the wire 110 a 2 for assistingextension of the left leg, continuously generates a tension in the wire110 a 4 for assisting extension of the right leg, generates no tensionin the wire 110 a 1 for assisting flexion of the left leg, and generatesno tension in the wire 110 a 3 for assisting flexion of the right leg.The tension of the wire 110 a 2 supports the left leg, which givessupport to the body when the user is at rest in the upright position,and the tension of the wire 110 a 4 supports the right leg, which givessupport to the body when the user is at rest in the upright position. Atthis time, if the leg bearing a larger load is the left leg, the drivecontrol unit 122 makes the tension to be generated in the wire 110 a 2greater than the tension to be generated in the wire 110 a 4 of theright leg, which bears a smaller load. If the leg bearing a larger loadis the right leg, the drive control unit 122 makes the tension to begenerated in the wire 110 a 4 greater than the tension to be generatedin the wire 110 a 2 of the left leg, which bears a smaller load.

If the leg bearing a larger load is the left leg, the first ratio isapplied to (tension to be generated in wire 110 a 2)/(tension to begenerated in wire 110 a 4). If the leg bearing a larger load is theright leg, the first ratio is applied to (tension to be generated inwire 110 a 4)/(tension to be generated in wire 110 a 2).

Further, the tension to be generated in the wire 110 a 2 of a legbearing a larger load when the user remains at rest is made less thanthe tension to be generated in the wire 110 a 2 of a leg bearing alarger load during walking. The tension to be generated in the wire 110a 4 of a leg bearing a larger load when the user remains at rest is madeless than the tension to be generated in the wire 110 a 4 of a legbearing a larger load during walking.

In addition, when the load applied to the contact sensor 301 a or 301 bof a hand carrying an object becomes zero, the drive control unit 122stops the operation of the assistance apparatus 100. That is, when theuser releases the object, the drive control unit 122 stops the operationof the assistance apparatus 100.

For example, FIG. 31 illustrates an example operation of the assistanceapparatus 100 over a period in which a user carrying an object only inthe left hand stops walking and releases the object. As illustrated inFIG. 31, the user stops walking at time point P1 and releases the objectfrom the left hand at time point P2. The assistance apparatus 100generates a tension of 60 N in the wire 110 a 2 and a tension of 40 N inthe wire 110 a 4 during the entirety of a period from the time point P1to the time point P2. In the illustrated example, the first ratio is“1.5”. Then, at the time point P2, the assistance apparatus 100 stopsits operation. If there is a wire in which a tension is being generatedat the time point P1, but in which no tension needs to be generatedafter the time point P1, such as the wire 110 a 3, the assistanceapparatus 100 may stop generating a tension in the wire at the timepoint P1 or may continuously generate a tension in the wire after thetime point P1 and stop generating a tension in the wire at apredetermined timing in accordance with the input profile. In the caseof the wire 110 a 3, the predetermined timing is a timing at which thethird period in the gait phase of the right leg ends.

As in this modification, when changing the balance between the wiretensions of the left and right legs in accordance with whether the firstcondition is satisfied and whether the second condition is satisfied,the assistance apparatus 100 may or may not apply a change in thebalance between the wire tensions of the left and right legs in theembodiment and/or the first modification. When a change in the balanceis applied, the assistance apparatus 100 can assist a user in walkingwhile carrying an object in one hand and in walking while carrying anobject in both hands.

-   3-3-3. Third Modification of Assistance Operation of Assistance    Apparatus

A third modification of the assistance operation of the assistanceapparatus 100 will be described. In the second modification, theassistance apparatus 100 identifies a hand in which a user carries anobject on the basis of the first condition and the second condition. Inthis modification, a hand in which a user carries an object isdesignated by the user via input to the input device 140 or the terminaldevice 150.

Referring to FIG. 3 and FIG. 8, when the input device 140 is used, theuser presses the “left-handed” button 145 or the “right-handed” button146 to determine a hand carrying an object. Upon receipt of a signalgenerated by the “left-handed” button 145 or the “right-handed” button146, the drive control unit 122 determines which of the left hand andthe right hand as a hand carrying an object. When the determined hand isthe left hand, the drive control unit 122 operates in a way similar tothat when the first condition is satisfied in the second modification.When the determined hand is the right hand, the drive control unit 122operates in a way similar to that when the second condition is satisfiedin the second modification. Accordingly, the assistance apparatus 100assists the user in walking while carrying an object in one hand in away similar to that in the second modification without requiring thedetection results of the contact sensors 301 a and 301 b. When the userstops walking, the drive control unit 122 may operate in a way similarto that in the second modification.

As in this modification, when changing the balance between the wiretensions of the left and right legs on the basis of informationdesignating a hand that carries an object, the assistance apparatus 100may or may not apply a change in the balance between the wire tensionsof the left and right legs in the embodiment, the first modification,and/or the second modification. When a change in the balance is applied,the assistance apparatus 100 can assist a user in walking while carryingan object in one hand and can assist a user in walking while carrying anobject in both hands. When a user carries an object in one hand, even ifthe user shifts the object from one hand to the other, the assistanceapparatus 100 can assist the user in walking in accordance with theshift.

-   3-3-4. Fourth Modification of Assistance Operation of Assistance    Apparatus

A fourth modification of the assistance operation of the assistanceapparatus 100 will be described. In this modification, when assisting auser in walking while carrying an object, the assistance apparatus 100operates in the following way. Specifically, the assistance apparatus100 increases the duration of assistance using the wires 110 a 2 and 110a 4 in the back part of the body of the user, compared with that in theexample illustrated in FIG. 25. For example, FIG. 32 illustrates amodification of the operation of the assistance apparatus 100 forassisting a user in walking forward while carrying an object. FIG. 32illustrates an example in which the assistance apparatus 100 assistsboth flexion and extension of the left and right legs of the user. Theassistance apparatus 100 produces a wire tension while changing the wiretension, with a maximum tension being 100 N.

When assisting flexion of a user during forward walking, the assistanceapparatus 100 generates wire tensions in the wire 110 a 1 of the leftleg and the wire 110 a 3 of the right leg in a way similar to that inthe example illustrated in FIG. 25.

When assisting extension of the left leg, for example, the assistanceapparatus 100 continuously generates a tension in the wire 110 a 2during the entirety of a second period, which is a period of 75% or moreand 120% or less of the gait phase of the left leg. Then, the assistanceapparatus 100 generates a wire tension greater than or equal to thefirst threshold value in the wire 110 a 2 during at least a portion ofthe second period. Then, the assistance apparatus 100 continuouslygenerates a tension greater than or equal to the fourth threshold valueand less than or equal to a fifth threshold value in the wire 110 a 2during the entirety of a sixth period, which is a period other than thesecond period in the gait phase of the left leg. The tension of the wire110 a 2 in the sixth period is greater than the tension of the wire 110a 1 in the fifth period other than the first period in the gait phase ofthe left leg and is greater than the tension of the wire 110 a 2 in thesixth period in the example illustrated in FIG. 25. Further, theassistance apparatus 100 continuously generates a tension, which isgreater than the wire tension in the sixth period, in the wire 110 a 2during the entirety of the second period. Thus, during an entire periodincluding the second period and the sixth period, the assistanceapparatus 100 continuously generates a tension greater than or equal tothe fourth threshold value in the wire 110 a 2. The fifth thresholdvalue is a value less than the maximum wire tension. The fifth thresholdvalue is, for example, a value given by an expression of maximumtension×0.6.

When assisting extension of the right leg, for example, the assistanceapparatus 100 continuously generates a tension in the wire 110 a 4during the entirety of a fourth period, which is a period of 75% or moreand 120% or less of the gait phase of the right leg. Then, theassistance apparatus 100 generates a wire tension greater than or equalto the first threshold value in the wire 110 a 4 during at least aportion of the fourth period. Then, the assistance apparatus 100continuously generates a tension greater than or equal to the fourththreshold value and less than or equal to the fifth threshold value inthe wire 110 a 4 during the entirety of an eighth period, which is aperiod other than the fourth period. The tension of the wire 110 a 4 inthe eighth period is greater than the tension of the wire 110 a 3 in theseventh period and is greater than the tension of the wire 110 a 4 inthe eighth period in the example illustrated in FIG. 25. Further, theassistance apparatus 100 continuously generates a tension, which isgreater than the wire tension in the eighth period, in the wire 110 a 4during the entirety of the fourth period. Thus, during an entire periodincluding the fourth period and the eighth period, the assistanceapparatus 100 continuously generates a tension greater than or equal tothe fourth threshold value in the wire 110 a 4.

As described above, a tension greater than or equal to the fourththreshold value is generated in the wires 110 a 2 and 110 a 4, which arelocated on or above the back part of the body of the user, during theentirety of a period over which the assistance apparatus 100 providesassistance. Thus, the user is subjected to the action such that the leftand right legs are pulled backward all the time during walking. When theuser is holding an object in the front part of the body, the center ofgravity of the body of the user tends to be moved forward. Thus, theuser, who is holding an object in the front part of the body, issubjected to the action such that the tensions of the wires 110 a 2 and110 a 4 cause the user to walk forward with the center of gravity of thebody being kept at the center of gravity position in the uprightposture. This enables the user to walk with a stable posture.Accordingly, the user is able to transport an object with comfort. Inthe fifth period, the tension of the wire 110 a 1 for assisting flexionof the left leg is small, and thus the action exerted by the tension ofthe wire 110 a 2 is achieved while being less affected by the tension ofthe wire 110 a 1. In the seventh period, the tension of the wire 110 a 3for assisting flexion of the right leg is small, and thus the actionexerted by the tension of the wire 110 a 4 is achieved while being lessaffected by the tension of the wire 110 a 3.

The assistance apparatus 100 may perform an operation according to thismodification so as to prevent a user from stumbling. By preventing auser from stumbling, the assistance apparatus 100 can prevent the userfrom falling. In this case, for example, the assistance apparatus 100generates substantially no wire tension, that is, generates a wiretension less than the fourth threshold value, in the wire 110 a 2 forassisting extension of the left leg during a portion of the sixth periodcorresponding to the swing phase of the left leg within the gait phaseof the left leg. The portion of the sixth period described above is, forexample, a period of more than 60% and less than 75% of the gait phaseof the left leg. Likewise, the assistance apparatus 100 makes thetension of the wire 110 a 4 for assisting extension of the right legless than the fourth threshold value over a portion of the eighth periodcorresponding to the swing phase of the right leg within the gait phaseof the right leg. The portion of the eighth period described above is,for example, a period of more than 60% and less than 75% of the gaitphase of the right leg. This enables the user to easily raise a leg offthe ground and prevents the user from dragging the toe across theground, level differences, or the like when raising the leg.

In addition, for example, the assistance apparatus 100 continuouslygenerates a wire tension greater than or equal to the fourth thresholdvalue and less than or equal to the fifth threshold value in the wire110 a 1 for assisting flexion of the left leg during the entirety of thefifth period in the gait phase of the left leg. The tension of the wire110 a 1 in the fifth period is greater than the tension of the wire 110a 1 in the fifth period in the example illustrated in FIG. 25. Thisenables the user to easily raise the left leg in the shift to flexion inthe first period. In addition, the assistance apparatus 100 continuouslygenerates a wire tension greater than or equal to the fourth thresholdvalue and less than or equal to the fifth threshold value in the wire110 a 3 for assisting flexion of the right leg during the entirety ofthe seventh period in the gait phase of the right leg. The tension ofthe wire 110 a 3 in the seventh period is greater than the tension ofthe wire 110 a 3 in the seventh period in the example illustrated inFIG. 25. This enables the user to easily raise the right leg in theshift to flexion in the third period. Thus, the assistance apparatus 100enables the user to easily raise a leg during flexion and can preventthe user from dragging the toe and stumbling.

Also in the wire tension control described above, the assistanceapparatus 100 may determine the first ratio on the basis of thedifference between the loads applied to the left and right hands of theuser and change the balance between the wire tensions of the left andright legs on the basis of the first ratio. Further, the assistanceapparatus 100 may determine the second ratio on the basis of informationon the dominant hand of the user and change the balance between the wiretensions of the left and right legs on the basis of the second ratio.Further, the assistance apparatus 100 may determine the third ratio onthe basis of the first condition and the second condition and change thebalance between the wire tensions of the left and right legs on thebasis of the third ratio. Further, the assistance apparatus 100 maydetermine the third ratio on the basis of information designating a handthat carries an object and change the balance between the wire tensionsof the left and right legs on the basis of the third ratio. In the casesdescribed above, the assistance apparatus 100 may change, for the wires110 a 2 and 110 a 4 in the back part of the body of the user, the wiretension in the entirety of the gait phase of the left leg and the wiretension in the entirety of the gait phase of the right leg to change thebalance or may change, for the wires 110 a 2 and 110 a 4 in the backpart of the body of the user, the wire tension in a portion of the gaitphase of the left leg and the wire tension in a portion of the gaitphase of the right leg to change the balance. For example, in the lattercase, the wire tension in the second period during the gait phase of theleft leg and the wire tension in the fourth period during the gait phaseof the right leg may be changed, and the wire tension in the sixthperiod during the gait phase of the left leg and the wire tension in theeighth period during the gait phase of the right leg may be changed.

-   3-3-5. Other Modifications of Assistance Operation of Assistance    Apparatus

The assistance apparatus 100 may not only assist a user in walkingforward while carrying an object but also assist a stationary user inlifting an object. In this case, the assistance apparatus 100 does notassist flexion but assists extension of the left and right legs. Whenlifting an object in front of the user, the user shifts from a stoopingor crouching position to an upright position. The user, who receives anassistance force for extension of both legs from the assistanceapparatus 100, can more easily achieve the shift from the stooping orcrouching position to the upright position.

During assistance, the assistance apparatus 100 generates a tensiongreater than a sixth threshold value in the wires 110 a 2 and 110 a 4 atthe same timing. The sixth threshold value is a value larger than thefirst threshold value and the fourth threshold value. The sixththreshold value is, for example, 60 N. The tensions of the wires 110 a 2and 110 a 4 for assisting the user in lifting an object may be greaterthan the tensions of the wires 110 a 2 and 110 a 4 for assisting a userin walking forward while carrying an object. The tensions of the wires110 a 2 and 110 a 4 may be generated at timings that are shifted withrespect to each other. The term “same timing” is used to include notonly exactly the same timing but also different timings or timings witha difference. The assistance apparatus 100 having the configurationdescribed above can assist a user in performing a series of motions fromlifting an object to transporting the object.

Also when assisting in lifting an object, the assistance apparatus 100may determine the first ratio on the basis of the difference between theloads applied to the left and right hands of the user and change thebalance between the tension of the second wire 110 a 2 of the left legand the tension of the fourth wire 110 a 4 of the right leg on the basisof the first ratio. Further, the assistance apparatus 100 may determinethe second ratio on the basis of information on the dominant hand of theuser and change the balance between the tensions of the wires 110 a 2and 110 a 4 on the basis of the second ratio. Further, the assistanceapparatus 100 may determine the third ratio on the basis of the firstcondition and the second condition and change the balance between thetensions of the wires 110 a 2 and 110 a 4 on the basis of the thirdratio. Further, the assistance apparatus 100 may determine the thirdratio on the basis of information designating a hand that carries anobject and change the balance between the tensions of the wires 110 a 2and 110 a 4 on the basis of the third ratio.

In the operation of the assistance apparatuses 100 and 200 according tothe embodiment and modification, the control unit 120 identifies a legbearing a larger load and a leg having a smaller load on the basis ofthe difference between the loads applied to the left and right hands ofthe user, which are detected via the contact sensors 301 a and 301 b,information on the dominant hand of the user, and/or informationdesignating a hand that carries an object and changes the balancebetween the tensions of the wires. The method for identifying a legbearing a larger load among the left and right legs is not limited tothat described above. The drive control unit 122 may identify a legbearing a larger load by using a sensor value of the pressure-sensitivesensor 302 or the inertial measurement unit 303. In this case, the drivecontrol unit 122 may identify a leg bearing a larger load in the waydescribed in the second modification.

In the respective operations of the assistance apparatuses 100 and 200according to the embodiment and the modification, the same input profileof wire tension and the same maximum wire tension are set for all thewires 110 for assisting flexion and extension. However, the presentdisclosure is not limited to the embodiment and the modificationdescribed above. Since the moment arms of the hip joints and the lengthsof the legs differ from one user to another, the assistance torqueexerted on the hip joint differs depending on the user even when thesame tension is applied to the same wire. The assistance torque isdetermined by an expression of wire tension x moment arm. Thus,different tensions may be applied to wires in accordance with the user.A fatter user has a larger moment arm of the hip joint than a thinneruser. Thus, for example, the maximum wire tension may be set to 60 N fora fat user with a girth of 100 cm or more, whereas the maximum wiretension may be set to 120 N for a thin user with a girth or 70 cm orless. This may make assistance torques exerted on a fat user and a thinuser equivalent.

In addition, the wire tension may change in accordance with the lengthsof the legs of the user. In assistance for flexion and extension, sincea vertical, or upward and downward, force component of wire tension ismore largely exerted on a user with longer legs, the wire tension for auser with longer legs may be reduced. Adjusting the wire tension foreach user in accordance with the body type and the leg length enables acomfortable assistance torque to be applied to each user.

In addition, the wire tensions on the front and back sides of the legsof the user are set to the same value. However, the present disclosureis not limited to the embodiment and the modification described above.For example, the tensions of the wires located on the front side of thelegs may be greater than the tensions of the wires located on the backside of the legs. Since the wires on the back side pass through thebuttocks of the user, the moment arm on the back side of the body of theuser is greater than that on the front side of the body of the user.Accordingly, the assistance torque exerted on the hip joints on the backside of the body of the user is greater than that on the front side ofthe body of the user. Thus, by increasing the tension of the wires onthe front side, the assistance apparatuses 100 and 200 can assistflexion and extension of the user on the front and back sides in awell-balanced manner.

The periods during which wire tensions are generated in the wires 110for assistance for flexion and extension are equal to each other.However, the present disclosure is not limited to the embodiment and themodification described above. For example, in the example illustrated inFIG. 25, the period during which a wire tension for assisting flexion isgenerated and the period during which a wire tension for assistingextension of the same leg is generated overlap. To reduce the overlapperiod, the length of either of the periods may be reduced. Inparticular, the periods may be adjusted such that the period in which awire tension greater than or equal to the first threshold value isgenerated during assistance for flexion does not overlap the period inwhich a wire tension greater than or equal to the first threshold valueis generated during assistance for extension. This also applies to theexamples illustrated in FIG. 27 to FIG. 32. This prevents the user frombeing confused by the simultaneous feeling of assistance for flexion andassistance for extension. The relationship between the period duringwhich a wire tension for assisting flexion is generated and the periodduring which a wire tension for assisting extension is generated may bedetermined in accordance with the flexion and extension ability of theuser.

In FIG. 25 and FIG. 27 to FIG. 32, the waveforms of the input profilesof wire tensions are convex curve. However, the present disclosure isnot limited to the illustrated examples. The waveforms of the inputprofiles illustrated in FIG. 25 and FIG. 27 to FIG. 32 are waveformsobtained through experiments, which are waveforms that allow users tofeel effective and comfortable when enjoying the benefits of assistanceprovided by the assistance apparatus 100. The input profiles of the wiretensions may be each created using, for example, a rectangular waveform,a trapezoidal waveform, a triangular waveform, a Gaussian waveform, orthe like. When a rectangular waveform is used, the assistance apparatus100 continuously generates a maximum tension during an entire periodover which a wire tension is generated. When a trapezoidal waveform isused, the assistance apparatus 100 continuously generates a maximumtension during an entire period over which a wire tension is generated,except the initial and terminal periods. When each input profile iscreated using a waveform that is quadrangle such as a rectangularwaveform and a trapezoidal waveform, a steep rise or a steep fall of thewire tension may occur. Such a change in tension may cause a user tofeel uncomfortable during assistance. Thus, for example, when thewaveform of each input profile is triangular, a rise of the wire tensionto the maximum tension may be changed to a gentler one, with the wiretension changing gradually. Accordingly, the assistance apparatus 100can carefully assist movements of the legs of the user, resulting in areduction in the risk of falling of the user due to a steep change inwire tension.

In actual human walking, flexion and extension torques produced by thelegs smoothly and continuously change. Thus, the waveform of each inputprofile may be implemented as a Gaussian waveform. The Gaussian waveformmay be a waveform created by, for example, adding together, orsuperposing, Gaussian functions by using a Gaussian function given byEquation (1) below. In this case, among superposition methods ofGaussian functions, a superposition method that is closest to thewaveform of a torque of the legs in actual human walking is found andapplied to the generation of a waveform of an input profile. Findingsuch a method is also referred to as Gaussian fitting. Accordingly,assistance torques can be applied to realize walking similar to actualhuman walking, and more natural assistance can be achieved.

$\begin{matrix}{{f(x)} = {\frac{1}{\sqrt{2\pi}\sigma}\exp \left\{ {- \frac{\left( {x - \mu} \right)^{2}}{2\sigma^{2}}} \right\}}} & (1)\end{matrix}$

Specifically, a Gaussian function has a pair of variables μ and σ (alsoreferred to as parameters), and the waveform of the Gaussian functiondepends on the two parameters. The time indicating a peak of a wave ofthe Gaussian function depends on the variable μ, and the width of thewave of the Gaussian function depends on the variable σ. Thus, variousGaussian functions may be generated by using various combinations ofvalues of the two parameters.

A function obtained by multiplying an amplitude of a torque generated ina leg during human walking by a Gaussian function forms a waveform thatshows time (in seconds) on the horizontal axis and torque (in Nm) on thevertical axis. Examples of the amplitude include a maximum torque of aleg during human walking, and the amplitude is, for example, 20 Nm.Gaussian functions are superposed to find a superposition method that isclosest to the torque-time waveform of the leg during actual humanwalking. At this time, Gaussian fitting is performed on actual humangait data by using n Gaussian functions f₁(x), f₂(x), . . . , andf_(n)(x) having various values of the two parameters μ and σ to obtainGaussian functions. The obtained Gaussian functions are furthersuperposed to obtain a new Gaussian function. By adjusting the twoparameters μ and σ of the new Gaussian function, an input profile of awire tension can be created.

Further, the assistance apparatus 100 may change the maximum tensions tobe generated in the wires 110 in accordance with the time of year whenthe user wears the assistance apparatus 100. For example, in summer whenthe user wears light clothes, the user's moment arm is shorter than thatin winter when the user wears thick clothes. Accordingly, even when theassistance apparatus 100 applies the same tension to the wires 110, thetorques exerted on the legs of the user in summer are smaller than thosein winter. Thus, for example, the assistance apparatus 100 may increasethe tension to be applied to each of the wires 110 in summer to, forexample, 1.2 times that in winter.

The operation of the assistance apparatus 200 according to themodification illustrated in FIG. 13 to FIG. 21 is also similar to thatof the assistance apparatus 100 according to the embodiment. For theoperations described above, the wire tension control for the first wire110 a 1 and the wire tension control for the fifth wire 110 a 5 of theassistance apparatus 200 are similar to the wire tension control for thewire 110 a 1 of the assistance apparatus 100. The wire tension controlfor the second wire 110 a 2 and the wire tension control for the sixthwire 110 a 6 of the assistance apparatus 200 are similar to the wiretension control for the wire 110 a 2 of the assistance apparatus 100.The wire tension control for the third wire 110 a 3 and the wire tensioncontrol for the seventh wire 110 a 7 of the assistance apparatus 200 aresimilar to the wire tension control for the wire 110 a 3 of theassistance apparatus 100. The wire tension control for the fourth wire110 a 4 and the wire tension control for the eighth wire 110 a 8 of theassistance apparatus 200 are similar to the wire tension control for thewire 110 a 4 of the assistance apparatus 100.

When assisting flexion or extension, the assistance apparatus 200generates tensions in two wires of the same leg at the same timing.Thus, the maximum tension to be generated in the first wire 110 a 1 andthe maximum tension to be generated in the fifth wire 110 a 5 of theassistance apparatus 200 may be different from the maximum tension to begenerated in the wire 110 a 1 of the assistance apparatus 100 and may besmaller than the maximum tension to be generated in the wire 110 a 1 ofthe assistance apparatus 100, for example. The maximum tension to begenerated in the second wire 110 a 2 and the maximum tension to begenerated in the sixth wire 110 a 6 of the assistance apparatus 200 maybe different from the maximum tension to be generated in the wire 110 a2 of the assistance apparatus 100 and may be smaller than the maximumtension to be generated in the wire 110 a 2 of the assistance apparatus100, for example. The maximum tension to be generated in the third wire110 a 3 and the maximum tension to be generated in the seventh wire 110a 7 of the assistance apparatus 200 may be different from the maximumtension to be generated in the wire 110 a 3 of the assistance apparatus100 and may be smaller than the maximum tension to be generated in thewire 110 a 3 of the assistance apparatus 100, for example. The maximumtension to be generated in the fourth wire 110 a 4 and the maximumtension to be generated in the eighth wire 110 a 8 of the assistanceapparatus 200 may be different from the maximum tension to be generatedin the wire 110 a 4 of the assistance apparatus 100 and may be smallerthan the maximum tension to be generated in the wire 110 a 4 of theassistance apparatus 100, for example.

The relationship between the maximum tension to be generated in thefirst wire 110 a 1 and the maximum tension to be generated in the fifthwire 110 a 5 of the assistance apparatus 200 and the maximum tension tobe generated in the wire 110 a 1 of the assistance apparatus 100 changesin accordance with the angle between the direction in which the wire 110a 1 of the assistance apparatus 100 extends and the direction in whichthe first wire 110 a 1 of the assistance apparatus 200 extends and inaccordance with the angle between the direction in which the wire 110 a1 of the assistance apparatus 100 extends and the direction in which thefifth wire 110 a 5 of the assistance apparatus 200 extends, and can bedetermined in accordance with the angles. The relationship between themaximum tension to be generated in the second wire 110 a 2 and themaximum tension to be generated in the sixth wire 110 a 6 of theassistance apparatus 200 and the maximum tension to be generated in thewire 110 a 2 of the assistance apparatus 100 changes in accordance withthe angle between the direction in which the wire 110 a 2 of theassistance apparatus 100 extends and the direction in which the secondwire 110 a 2 of the assistance apparatus 200 extends and in accordancewith the angle between the direction in which the wire 110 a 2 of theassistance apparatus 100 extends and the direction in which the sixthwire 110 a 6 of the assistance apparatus 200 extends, and can bedetermined in accordance with the angles. The relationship between themaximum tension to be generated in the third wire 110 a 3 and themaximum tension to be generated in the seventh wire 110 a 7 of theassistance apparatus 200 and the maximum tension to be generated in thewire 110 a 3 of the assistance apparatus 100 changes in accordance withthe angle between the direction in which the wire 110 a 3 of theassistance apparatus 100 extends and the direction in which the thirdwire 110 a 3 of the assistance apparatus 200 extends and in accordancewith the angle between the direction in which the wire 110 a 3 of theassistance apparatus 100 extends and the direction in which the seventhwire 110 a 7 of the assistance apparatus 200 extends, and can bedetermined in accordance with the angles. The relationship between themaximum tension to be generated in the fourth wire 110 a 4 and themaximum tension to be generated in the eighth wire 110 a 8 of theassistance apparatus 200 and the maximum tension to be generated in thewire 110 a 4 of the assistance apparatus 100 changes in accordance withthe angle between the direction in which the wire 110 a 4 of theassistance apparatus 100 extends and the direction in which the fourthwire 110 a 4 of the assistance apparatus 200 extends and in accordancewith the angle between the direction in which the wire 110 a 4 of theassistance apparatus 100 extends and the direction in which the eighthwire 110 a 8 of the assistance apparatus 200 extends, and can bedetermined in accordance with the angles.

The term “same timing” is used to include not only exactly the sametiming but also different timings or timings with a difference. Thedifference may be less than 10% or may be 5% or less in terms of thevalue of the gait phase. For example, when the difference is 5% or less,the values at all timings in the gait phase are included in a range ofvalues of the gait phase, which is within ±5% from an average value ofvalues at the timings in the gait phase.

4. EXAMPLES

An experiment was made for the assistance operation using the assistanceapparatus 100 according to the embodiment to compare and verify therelationships between ways in which a user carries an object and thebalance between the wire tensions of the left and right legs.Specifically, a method for carrying an object in Case 1 and a method forcarrying an object in Case 2 were verified. In Case 1, as illustrated inFIG. 26B, a user carried an object in the left and right hands atdifferent height positions. In Case 2, as illustrated in FIG. 26C, auser carried an object in one hand.

In Case 1, the operations of the assistance apparatus 100 in Example 1,Comparative Example 1, and Comparative Example 2 were verified. InExample 1, as in the embodiment, the assistance apparatus 100 operatedin such a manner that the wire tension of the leg on the same side asthe hand carrying the object at the lower position was set to be twicethe wire tension of the leg on the same side as the hand carrying theobject at the higher position. For example, in FIG. 26B, the wiretension of the left leg is set to be twice the wire tension of the rightleg. In Example 1, the assistance apparatus 100 controlled the tensionsof the wires 110 in accordance with input profiles similar to thoseillustrated in FIG. 28.

In Comparative Example 1, the assistance apparatus 100 operated with thebalance between the wire tensions of the left and right legs opposite tothat in Example 1. Specifically, the assistance apparatus 100 operatedin such a manner that the wire tension of the leg on the same side asthe hand carrying the object at the higher position was set to be twicethe wire tension of the leg on the same side as the hand carrying theobject at the lower position. In this case, the assistance apparatus 100controlled the tensions of the wires 110 in accordance with inputprofiles in which the ratio of the wire tensions of the left and rightlegs in the input profiles of wire tensions used in Example 1 wasreversed.

In Comparative Example 2, the assistance apparatus 100 operated in sucha manner that the wire tension of the leg on the same side as the handcarrying the object at the lower position and the wire tension of theleg on the same side as the hand carrying the object at the higherposition were equal. In this case, the assistance apparatus 100controlled the tensions of the wires 110 in accordance with the inputprofiles illustrated in FIG. 25.

In Case 2, the operations of the assistance apparatus 100 in Example 2,Comparative Example 3, and Comparative Example 4 were verified. InExample 2, as in the second modification, the assistance apparatus 100operated in such a manner that the wire tension for assisting extensionof the leg on the same side as a hand carrying an object was set to betwice the wire tension for assisting extension of the leg on the sameside as a hand not carrying the object and the wire tension forassisting flexion of the leg on the same side as the hand not carryingthe object was set to be twice the wire tension for assisting flexion ofthe leg on the same side as the hand carrying the object. For example,in FIG. 26C, the wire tension for assisting extension of the left legand flexion of the right leg is set to be twice the wire tension forassisting extension of the right leg and flexion of the left leg. InExample 2, the assistance apparatus 100 controlled the tensions of thewires 110 in accordance with input profiles similar to those illustratedin FIG. 29.

In Comparative Example 3, the assistance apparatus 100 operated with thebalance between the wire tensions of the left and right legs opposite tothat in Example 2. Specifically, the assistance apparatus 100 operatedin such a manner that the wire tension for assisting extension of theleg on the same side as a hand not carrying an object was set to betwice the wire tension for assisting extension of the leg on the sameside as a hand carrying the object and the wire tension for assistingflexion of the leg on the same side as the hand carrying the object wasset to be twice the wire tension for assisting flexion of the leg on thesame side as the hand not carrying the object. In this case, theassistance apparatus 100 controlled the tensions of the wires 110 inaccordance with input profiles in which the wire tensions for assistingextension and flexion of the same leg in the input profiles of wiretensions used in Example 2 were reversed.

In Comparative Example 4, the assistance apparatus 100 operated in sucha manner that the wire tension of the leg on the same side as a handcarrying an object and the wire tension of the leg on the same side as ahand not carrying the object were equal. In this case, the assistanceapparatus 100 controlled the tensions of the wires 110 in accordancewith the input profiles illustrated in FIG. 25.

In Examples 1 and 2 and Comparative Examples 1 to 4, the maximumtensions that could be generated in the wires 110 a 1 to 110 a 4 wereeach set to 100 N.

The experiment was conducted on four subjects, namely A to D. Thesubjects A, C, and D were males, and the subject B was female. All thesubjects A to D wearing the assistance apparatus 100 received threetypes of assistance in Example 1, Comparative Example 1, and ComparativeExample 2 when walking forward in Case 1, and received three types ofassistance in Example 2, Comparative Example 3, and Comparative Example4 when walking forward in Case 2. Then, the subjects A to D selected oneoptimum operation, which was the most comfortable walking operation, ineach of Cases 1 and 2. The selection results are given in Table 1 below.Table 1 indicates that Examples 1 and 2 provide effective assistance forwalking of a subject. Table 1 also indicates that Comparative Examples 2and 4 also allow a subject to feel the effect of assistance.

TABLE 1 Evaluation results of assistance based on operations in patternsCase 1 Case 2 Comparative Comparative Comparative Comparative SubjectExample 1 Example 1 Example 2 Example 2 Example 3 Example 4 A OptimumOptimum B Optimum Optimum C Optimum Optimum D Optimum Optimum

5. Other Embodiments

While an assistance apparatus and so on according to one or more aspectshave been described in conjunction with an embodiment and amodification, the present disclosure is not limited to the embodimentand modification. Applications of various modifications conceived of bypersons skilled in the art to this embodiment and modification andembodiments based on combinations of constituent elements in differentembodiments and modifications may also be encompassed in the scope ofone or more aspects as long as such applications or embodiments do notdepart from the gist of the present disclosure.

For example, in the assistance apparatuses 100 and 200 according to theembodiment and modification, the timings at which the control unit 120activates the motors 114 to generate tensions in the wires 110 andvalues of the gait phase regarding the input profiles of the tensionsare not limited to the values described in the embodiment andmodification. The timings and the values of the gait phase regarding theinput profiles of the tensions may be different from those described inthe embodiment and modification. For example, an error of severalpercent in terms of gait phase may occur.

In the assistance apparatuses 100 and 200 according to the embodimentand modification, each of the wires 110 is provided with a motor.However, the present disclosure is not limited to the embodiment andmodification. One motor may be coupled to wires. For example, in theassistance apparatus 200, one motor may pull the wires 110 a 1 and 110 a5. That is, the assistance apparatus 200 may include, for example, fourmotors so that one motor is provided for two wires.

In the assistance apparatuses 100 and 200 according to the embodimentand the modification, four wires or eight wires are used to couple theupper-body belt 111 to the knee belts 112 a and 112 b. That is, twowires or four wires are coupled to each knee belt. However, the numberof wires to be coupled to each knee belt is not limited to thatdescribed above. Any number of wires more than one may be coupled toeach knee belt. For example, the numbers of wires to be coupled to thefront part and the back part of each knee belt may be different. Flexionof the left leg may mean flexion of the hip joint of the left leg.Flexion of the right leg may mean flexion of the hip joint of the rightleg. Extension of the left leg may mean extension of the hip joint ofthe left leg. Extension of the right leg may mean extension of the hipjoint of the right leg.

The present disclosure is applicable to an apparatus for assisting auser in changing direction.

What is claimed is:
 1. An assistance apparatus comprising: an upper-bodybelt to be worn on an upper half of a body of a user; a left knee beltto be worn on a left knee of the user; a right knee belt to be worn on aright knee of the user; a first wire that couples the upper-body beltand the left knee belt to each other on or above a front part of thebody of the user; a second wire that couples the upper-body belt and theleft knee belt to each other on or above a back part of the body of theuser; a third wire that couples the upper-body belt and the right kneebelt to each other on or above the front part of the body of the user; afourth wire that couples the upper-body belt and the right knee belt toeach other on or above the back part of the body of the user; at leastone motor; a left sensor attachable to a left hand of the user; a rightsensor attachable to a right hand of the user; and a control circuit,wherein when the assistance apparatus assists the user in walking whilecarrying an object, the at least one motor generates (i) a tensiongreater than or equal to a first threshold value in the first wireduring a first period, the first period being a period of 35% or moreand 90% or less of a gait phase of a left leg of the user, (ii) atension greater than or equal to the first threshold value in the secondwire during a second period, the second period being a period of 0% ormore and 25% or less and 65% or more and less than 100% of the gaitphase of the left leg, (iii) a tension greater than or equal to thefirst threshold value in the third wire during a third period, the thirdperiod being a period of 35% or more and 90% or less of a gait phase ofa right leg of the user, and (iv) a tension greater than or equal to thefirst threshold value in the fourth wire during a fourth period, thefourth period being a period of 0% or more and 25% or less and 65% ormore and less than 100% of the gait phase of the right leg, the controlcircuit acquires a left sensor value from the left sensor and a rightsensor value from the right sensor, the control circuit detects a firstcondition or a second condition, the first condition being a conditionin which the left sensor value is greater than or equal to a secondthreshold value and in which the right sensor value is smaller than thesecond threshold value, the second condition being a condition in whichthe right sensor value is greater than or equal to the second thresholdvalue and in which the left sensor value is smaller than the secondthreshold value, when the first condition is detected, the at least onemotor makes the tension of the second wire in the second period and thetension of the third wire in the third period greater than the tensionof the first wire in the first period and the tension of the fourth wirein the fourth period, and when the second condition is detected, the atleast one motor makes the tension of the first wire in the first periodand the tension of the fourth wire in the fourth period greater than thetension of the second wire in the second period and the tension of thethird wire in the third period.
 2. An assistance apparatus comprising:an upper-body belt to be worn on an upper half of a body of a user; aleft knee belt to be worn on a left knee of the user; a right knee beltto be worn on a right knee of the user; a first wire that couples theupper-body belt and the left knee belt to each other on or above a frontpart of the body of the user; a second wire that couples the upper-bodybelt and the left knee belt to each other on or above a back part of thebody of the user; a third wire that couples the upper-body belt and theright knee belt to each other on or above the front part of the body ofthe user; a fourth wire that couples the upper-body belt and the rightknee belt to each other on or above the back part of the body of theuser; at least one motor; and a control circuit, wherein when theassistance apparatus assists the user in walking while carrying anobject, the at least one motor generates (i) a tension greater than orequal to a first threshold value in the first wire during a firstperiod, the first period being a period of 35% or more and 90% or lessof a gait phase of a left leg of the user, (ii) a tension greater thanor equal to the first threshold value in the second wire during a secondperiod, the second period being a period of 0% or more and 25% or lessand 65% or more and less than 100% of the gait phase of the left leg,(iii) a tension greater than or equal to the first threshold value inthe third wire during a third period, the third period being a period of35% or more and 90% or less of a gait phase of a right leg of the user,and (iv) a tension greater than or equal to the first threshold value inthe fourth wire during a fourth period, the fourth period being a periodof 0% or more and 25% or less and 65% or more and less than 100% of thegait phase of the right leg, the control circuit acquires informationspecifying a hand that carries the object, when the informationindicates a left hand of the user, the at least one motor makes thetension of the second wire in the second period and the tension of thethird wire in the third period greater than the tension of the firstwire in the first period and the tension of the fourth wire in thefourth period, and when the information indicates a right hand of theuser, the at least one motor makes the tension of the first wire in thefirst period and the tension of the fourth wire in the fourth periodgreater than the tension of the second wire in the second period and thetension of the third wire in the third period.
 3. The assistanceapparatus according to claim 2, further comprising an interface device,wherein the control circuit receives the information via the interfacedevice.
 4. The assistance apparatus according to claim 1, wherein theleft leg shifts from a stance phase to a swing phase during the firstperiod, the left leg shifts from the swing phase to the stance phaseduring the second period, the right leg shifts from the stance phase tothe swing phase during the third period, and the right leg shifts fromthe swing phase to the stance phase during the fourth period.
 5. Theassistance apparatus according to claim 1, wherein the at least onemotor includes a first motor, a second motor, a third motor, and afourth motor, the first wire has a first end fixed to the left kneebelt, the first wire has a second end fixed to the first motor, thesecond wire has a first end fixed to the left knee belt, the second wirehas a second end fixed to the second motor, the third wire has a firstend fixed to the right knee belt, the third wire has a second end fixedto the third motor, the fourth wire has a first end fixed to the rightknee belt, and the fourth wire has a second end fixed to the fourthmotor.
 6. The assistance apparatus according to claim 1, furthercomprising: a fifth wire that couples the upper-body belt and the leftknee belt to each other and that extends on or above the front part ofthe body of the user in a direction crossing a direction in which thefirst wire extends; a sixth wire that couples the upper-body belt andthe left knee belt to each other and that extends on or above the backpart of the body of the user in a direction crossing a direction inwhich the second wire extends; a seventh wire that couples theupper-body belt and the right knee belt to each other and that extendson or above the front part of the body of the user in a directioncrossing a direction in which the third wire extends; and an eighth wirethat couples the upper-body belt and the right knee belt to each otherand that extends on or above the back part of the body of the user in adirection crossing a direction in which the fourth wire extends, whereinwhen the assistance apparatus assists the user in walking while carryingthe object, the at least one motor generates (i) a tension greater thanor equal to the first threshold value in the first wire and the fifthwire during the first period, (ii) a tension greater than or equal tothe first threshold value in the second wire and the sixth wire duringthe second period, (iii) a tension greater than or equal to the firstthreshold value in the third wire and the seventh wire during the thirdperiod, and (iv) a tension greater than or equal to the first thresholdvalue in the fourth wire and the eighth wire during the fourth period.7. The assistance apparatus according to claim 1, wherein a time pointof 50% of the gait phase of the left leg corresponds to a time point of0% of the gait phase of the right leg, and a time point of 50% of thegait phase of the right leg corresponds to a time point of 0% of thegait phase of the left leg.
 8. The assistance apparatus according toclaim 1, further comprising a memory, wherein the memory stores aprogram for controlling the at least one motor, and the control circuitcontrols the at least one motor in accordance with the program.
 9. Theassistance apparatus according to claim 1, further comprising a gaitsensor that detects a gait cycle of the user, wherein the controlcircuit calculates the gait phase of the left leg and the gait phase ofthe right leg based on a sensor value of the gait sensor.
 10. Anassistance method for assisting a movement of a user by using wiresattached to a body of the user, the assistance method comprising:coupling, using a first wire among the wires, an upper-body belt and aleft knee belt to each other on or above a front part of the body of theuser, the upper-body belt being a belt to be worn on an upper half ofthe body of the user, the left knee belt being a belt to be worn on aleft knee of the user; coupling, using a second wire among the wires,the upper-body belt and the left knee belt to each other on or above aback part of the body of the user; coupling, using a third wire amongthe wires, the upper-body belt and a right knee belt to each other on orabove the front part of the body of the user, the right knee belt beinga belt to be worn on a right knee of the user; coupling, using a fourthwire among the wires, the upper-body belt and the right knee belt toeach other on or above the back part of the body of the user; whenassisting the user in walking while carrying an object, generating atension greater than or equal to a first threshold value in the firstwire during a first period, the first period being a period of 35% ormore and 90% or less of a gait phase of a left leg of the user;generating a tension greater than or equal to the first threshold valuein the second wire during a second period, the second period being aperiod of 0% or more and 25% or less and 65% or more and less than 100%of the gait phase of the left leg; generating a tension greater than orequal to the first threshold value in the third wire during a thirdperiod, the third period being a period of 35% or more and 90% or lessof a gait phase of a right leg of the user; generating a tension greaterthan or equal to the first threshold value in the fourth wire during afourth period, the fourth period being a period of 0% or more and 25% orless and 65% or more and less than 100% of the gait phase of the rightleg; acquiring a left sensor value from a left sensor attached to a lefthand of the user; acquiring a right sensor value from a right sensorattached to a right hand of the user; detecting a first condition or asecond condition, the first condition being a condition in which theleft sensor value is greater than or equal to a second threshold valueand in which the right sensor value is smaller than the second thresholdvalue, the second condition being a condition in which the right sensorvalue is greater than or equal to the second threshold value and inwhich the left sensor value is smaller than the second threshold value;when the first condition is detected, making the tension of the secondwire in the second period and the tension of the third wire in the thirdperiod greater than the tension of the first wire in the first periodand the tension of the fourth wire in the fourth period; and when thesecond condition is detected, making the tension of the first wire inthe first period and the tension of the fourth wire in the fourth periodgreater than the tension of the second wire in the second period and thetension of the third wire in the third period, wherein the tension ofthe first wire, the tension of the second wire, the tension of the thirdwire, and the tension of the fourth wire are adjusted by a motor that iscontrolled by at least one control circuit.
 11. An assistance method forassisting a movement of a user by using wires attached to a body of theuser, the assistance method comprising: coupling, using a first wireamong the wires, an upper-body belt and a left knee belt to each otheron or above a front part of the body of the user, the upper-body beltbeing a belt to be worn on an upper half of the body of the user, theleft knee belt being a belt to be worn on a left knee of the user;coupling, using a second wire among the wires, the upper-body belt andthe left knee belt to each other on or above a back part of the body ofthe user; coupling, using a third wire among the wires, the upper-bodybelt and a right knee belt to each other on or above the front part ofthe body of the user, the right knee belt being a belt to be worn on aright knee of the user; coupling, using a fourth wire among the wires,the upper-body belt and the right knee belt to each other on or abovethe back part of the body of the user; when assisting the user inwalking while carrying an object, generating a tension greater than orequal to a first threshold value in the first wire during a firstperiod, the first period being a period of 35% or more and 90% or lessof a gait phase of a left leg of the user; generating a tension greaterthan or equal to the first threshold value in the second wire during asecond period, the second period being a period of 0% or more and 25% orless and 65% or more and less than 100% of the gait phase of the leftleg; generating a tension greater than or equal to the first thresholdvalue in the third wire during a third period, the third period being aperiod of 35% or more and 90% or less of a gait phase of a right leg ofthe user; generating a tension greater than or equal to the firstthreshold value in the fourth wire during a fourth period, the fourthperiod being a period of 0% or more and 25% or less and 65% or more andless than 100% of the gait phase of the right leg; acquiring informationspecifying a hand that carries the object; when the informationindicates a left hand of the user, making the tension of the second wirein the second period and the tension of the third wire in the thirdperiod greater than the tension of the first wire in the first periodand the tension of the fourth wire in the fourth period; and when theinformation indicates a right hand of the user, making the tension ofthe first wire in the first period and the tension of the fourth wire inthe fourth period greater than the tension of the second wire in thesecond period and the tension of the third wire in the third period,wherein the tension of the first wire, the tension of the second wire,the tension of the third wire, and the tension of the fourth wire areadjusted by a motor that is controlled by at least one control circuit.12. The assistance method according to claim 11, further comprisingacquiring the information via an interface device.
 13. The assistancemethod according to claim 10, wherein the left leg shifts from a stancephase to a swing phase during the first period, the left leg shifts fromthe swing phase to the stance phase during the second period, the rightleg shifts from the stance phase to the swing phase during the thirdperiod, and the right leg shifts from the swing phase to the stancephase during the fourth period.
 14. The assistance method according toclaim 10, wherein a first end of the first wire is fixed to the leftknee belt, a second end of the first wire is fixed to a first motoramong the at least one motor, a first end of the second wire is fixed tothe left knee belt, a second end of the second wire is fixed to a secondmotor among the at least one motor, a first end of the third wire isfixed to the right knee belt, a second end of the third wire is fixed toa third motor among the at least one motor, a first end of the fourthwire is fixed to the right knee belt, and a second end of the fourthwire is fixed to a fourth motor among the at least one motor.
 15. Theassistance method according to claim 10, further comprising: coupling,using a fifth wire among the wires, the upper-body belt and the leftknee belt to each other, the fifth wire extending on or above the frontpart of the body of the user in a direction crossing a direction inwhich the first wire extends; coupling, using a sixth wire among thewires, the upper-body belt and the left knee belt to each other, thesixth wire extending on or above the back part of the body of the userin a direction crossing a direction in which the second wire extends;coupling, using a seventh wire among the wires, the upper-body belt andthe right knee belt to each other, the seventh wire extending on orabove the front part of the body of the user in a direction crossing adirection in which the third wire extends; coupling, using an eighthwire among the wires, the upper-body belt and the right knee belt toeach other, the eighth wire extending on or above the back part of thebody of the user in a direction crossing a direction in which the fourthwire extends; when assisting the user in walking while carrying theobject, generating a tension greater than or equal to the firstthreshold value in the first wire and the fifth wire during the firstperiod; generating a tension greater than or equal to the firstthreshold value in the second wire and the sixth wire during the secondperiod; generating a tension greater than or equal to the firstthreshold value in the third wire and the seventh wire during the thirdperiod; and generating a tension greater than or equal to the firstthreshold value in the fourth wire and the eighth wire during the fourthperiod.
 16. The assistance method according to claim 10, wherein a timepoint of 50% of the gait phase of the left leg corresponds to a timepoint of 0% of the gait phase of the right leg, and a time point of 50%of the gait phase of the right leg corresponds to a time point of 0% ofthe gait phase of the left leg.
 17. The assistance method according toclaim 10, further comprising: acquiring a sensor value of a gait sensorthat detects a gait cycle of the user; and calculating the gait phase ofthe left leg and the gait phase of the right leg based on the sensorvalue.
 18. A recording medium storing a control program for causing adevice including a processor to execute a process, the recording mediumbeing a non-volatile, computer-readable medium, a first wire coupling anupper-body belt and a left knee belt to each other on or above a frontpart of a body of a user, the upper-body belt being a belt to be worn onan upper half of the body of the user, the left knee belt being a beltto be worn on a left knee of the user, a second wire coupling theupper-body belt and the left knee belt to each other on or above a backpart of the body of the user, a third wire coupling the upper-body beltand a right knee belt to each other on or above the front part of thebody of the user, the right knee belt being a belt to be worn on a rightknee of the user, a fourth wire coupling the upper-body belt and theright knee belt to each other on or above the back part of the body ofthe user, the process comprising: when assisting the user in walkingwhile carrying an object, causing at least one motor to generate atension greater than or equal to a first threshold value in the firstwire during a first period, the first period being a period of 35% ormore and 90% or less of a gait phase of a left leg of the user; causingthe at least one motor to generate a tension greater than or equal tothe first threshold value in the second wire during a second period, thesecond period being a period of 0% or more and 25% or less and 65% ormore and less than 100% of the gait phase of the left leg; causing theat least one motor to generate a tension greater than or equal to thefirst threshold value in the third wire during a third period, the thirdperiod being a period of 35% or more and 90% or less of a gait phase ofa right leg of the user; causing the at least one motor to generate atension greater than or equal to the first threshold value in the fourthwire during a fourth period, the fourth period being a period of 0% ormore and 25% or less and 65% or more and less than 100% of the gaitphase of the right leg; acquiring a left sensor value from a left sensorattached to a left hand of the user; acquiring a right sensor value froma right sensor attached to a right hand of the user; detecting a firstcondition or a second condition, the first condition being a conditionin which the left sensor value is greater than or equal to a secondthreshold value and in which the right sensor value is smaller than thesecond threshold value, the second condition being a condition in whichthe right sensor value is greater than or equal to the second thresholdvalue and in which the left sensor value is smaller than the secondthreshold value; when the first condition is detected, making thetension of the second wire in the second period and the tension of thethird wire in the third period greater than the tension of the firstwire in the first period and the tension of the fourth wire in thefourth period; and when the second condition is detected, making thetension of the first wire in the first period and the tension of thefourth wire in the fourth period greater than the tension of the secondwire in the second period and the tension of the third wire in the thirdperiod.
 19. A recording medium storing a control program for causing adevice including a processor to execute a process, the recording mediumbeing a non-volatile, computer-readable medium, a first wire coupling anupper-body belt and a left knee belt to each other on or above a frontpart of a body of a user, the upper-body belt being a belt to be worn onan upper half of the body of the user, the left knee belt being a beltto be worn on a left knee of the user, a second wire coupling theupper-body belt and the left knee belt to each other on or above a backpart of the body of the user, a third wire coupling the upper-body beltand a right knee belt to each other on or above the front part of thebody of the user, the right knee belt being a belt to be worn on a rightknee of the user, a fourth wire coupling the upper-body belt and theright knee belt to each other on or above the back part of the body ofthe user, the process comprising: when assisting the user in walkingwhile carrying an object, causing at least one motor to generate atension greater than or equal to a first threshold value in the firstwire during a first period, the first period being a period of 35% ormore and 90% or less of a gait phase of a left leg of the user; causingthe at least one motor to generate a tension greater than or equal tothe first threshold value in the second wire during a second period, thesecond period being a period of 0% or more and 25% or less and 65% ormore and less than 100% of the gait phase of the left leg; causing theat least one motor to generate a tension greater than or equal to thefirst threshold value in the third wire during a third period, the thirdperiod being a period of 35% or more and 90% or less of a gait phase ofa right leg of the user; causing the at least one motor to generate atension greater than or equal to the first threshold value in the fourthwire during a fourth period, the fourth period being a period of 0% ormore and 25% or less and 65% or more and less than 100% of the gaitphase of the right leg; acquiring information specifying a hand thatcarries the object; when the information indicates a left hand of theuser, making the tension of the second wire in the second period and thetension of the third wire in the third period greater than the tensionof the first wire in the first period and the tension of the fourth wirein the fourth period; and when the information indicates a right hand ofthe user, making the tension of the first wire in the first period andthe tension of the fourth wire in the fourth period greater than thetension of the second wire in the second period and the tension of thethird wire in the third period.
 20. An assistance apparatus, comprising:a first belt to be worn on an upper half of a body of a user; a leftknee belt to be worn above a left knee of the user; a right knee belt tobe worn above a right knee of the user; a first wire coupling the firstbelt with the left knee belt on or above a front part of the body; asecond wire coupling the first belt with the left knee belt on or abovea back part of the body; a third wire coupling the first belt with theright knee belt on or above the front part; a fourth wire coupling thefirst belt with the right knee belt on or above the back part; a motor;a left sensor to be worn on a left hand of the user; a right sensor tobe worn on a right hand of the user; and a controller, wherein when theassistance apparatus assistances the user in walking, (a) the motorgenerates a first tension on the first wire during a first period beingfrom a first percent of a TL(i) to a second percent of the TL(i), thefirst percent is 35 percent or more and 55 percent or less, the secondpercent is 80 percent or more and 90 percent or less, a magnitude of thefirst tension being a first threshold vale or more, the TL(i) being anith gait cycle of a left leg of the user, (b) the motor generates asecond tension on the second wire during a second period being from zeropercent of the TL(i) to a third percent of the TL(i) and being from afourth percent of the TL(i) to 100 percent of the TL(i), the thirdpercent is 10 percent or more and 25 percent or less, the fourth percentis 65 percent or more and 90 percent or less, (c) the motor generates athird tension on the third wire during a third period being from a fifthpercent of a TR(i) to a sixth percent of the TR(i), the fifth percent is35 percent or more and 55 percent or less, the sixth percent is 80percent or more and 90 percent or less, a magnitude of the third tensionbeing the first threshold vale or more, the TR(i) being an ith gaitcycle of a right leg of the user, and (d) the motor generates a fourthtension on the fourth wire during a fourth period being from zeropercent of the TR(i) to a seventh percent of the TL(i) and being from aneighth percent of the TL(i) to 100 percent of the TL(i), the seventhpercent is 10 percent or more and 25 percent or less, the eighth percentis 65 percent or more and 90 percent or less, wherein the controllerobtains a left weight value from the left sensor and a right weightvalue from the right sensor, wherein the controller obtains a leftweight value from the left sensor and a right weight value from theright sensor, wherein when the controller detects a first condition thatthe left sensor detects a weight equal to or more than a secondthreshold value based on the left weight value and the right sensordetects no weight based on the right weight value, a maximum value ofthe second tension and a maximum value of the third tension are biggerthan a maximum value of the first tension and a maximum value of thefourth tension, and wherein when the controller detects a secondcondition that the left sensor detects no weight based on the leftweight value and the right sensor detects a weight equal to or more thanthe second threshold value based on the right weight value, a maximumvalue of the first tension and a maximum value of the fourth tension arebigger than a maximum value of the second tension and a maximum value ofthe third tension.